# General Usage

**URL:** https://discourse.julialang.org/c/usage/6.md?page=866

[Latest](https://discourse.julialang.org/latest.md) · [Categories](https://discourse.julialang.org/categories.md) · [Tags](https://discourse.julialang.org/tags.md)

**Page:** 867

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## [Propagating exceptions from MATLAB to Julia](https://discourse.julialang.org/t/propagating-exceptions-from-matlab-to-julia/24177)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 0\
**Last updated:** [May 13, 2019, 2:34pm UTC](https://discourse.julialang.org/t/propagating-exceptions-from-matlab-to-julia/24177 "2019-05-13T14:34:50Z")

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I’ve posted an issue mentioning this in MATLAB.jl a few months ago, but maybe someone here has an idea. I’m looking for a way to have exceptions inside Matlab propagate to Julia. Right now they might elicit some printout…

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## [Array Type and Values-as-Parameters Performance penalty?](https://discourse.julialang.org/t/array-type-and-values-as-parameters-performance-penalty/24092)

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**Author:** [@ianfiske](https://discourse.julialang.org/u/ianfiske)\
**Replies:** 2\
**Last updated:** [May 13, 2019, 12:39pm UTC](https://discourse.julialang.org/t/array-type-and-values-as-parameters-performance-penalty/24092 "2019-05-13T12:39:52Z")

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The user manual at Performance Tips · The Julia Language suggests that we avoid types with values as parameters. However, doesn’t the base Array{T, N} have a value-parameter N? How can Base get away with this but have …

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## [Help to build a macro to mimic the With of VBA](https://discourse.julialang.org/t/help-to-build-a-macro-to-mimic-the-with-of-vba/24116)

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**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 14\
**Last updated:** [May 13, 2019, 11:03am UTC](https://discourse.julialang.org/t/help-to-build-a-macro-to-mimic-the-with-of-vba/24116 "2019-05-13T11:03:14Z")

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Hi guys! Sometimes, the With feature of VBA can be very useful. Consider something like: general.insert("simProgress", generalFrame.simProgress); general.insert("simulationDate", simulationDate); general.in…

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## ['FallBack Renderer" checkbox to gain terminal speed in juno Atom](https://discourse.julialang.org/t/fallback-renderer-checkbox-to-gain-terminal-speed-in-juno-atom/24165)

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**Author:** [@Ajaychat3](https://discourse.julialang.org/u/Ajaychat3)\
**Replies:** 4\
**Last updated:** [May 13, 2019, 10:44am UTC](https://discourse.julialang.org/t/fallback-renderer-checkbox-to-gain-terminal-speed-in-juno-atom/24165 "2019-05-13T10:44:02Z")

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I am using Julia 1.1.0 on ubuntu 18.04 LTS. I have notices that the by checking the checkbox " Fallback Renderer", the response of julia terminal get improved. However, If I close and reopen Atom, the response rate of ju…

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## [JuliaInXL on macOS](https://discourse.julialang.org/t/juliainxl-on-macos/24166)

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**Author:** [@askvorts](https://discourse.julialang.org/u/askvorts)\
**Replies:** 0\
**Last updated:** [May 13, 2019, 9:16am UTC](https://discourse.julialang.org/t/juliainxl-on-macos/24166 "2019-05-13T09:16:11Z")

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I was wondering if there are plans to support JuliaInXL on macOS in the near future? Thank you

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## [Web Julia Roadmap Assessment](https://discourse.julialang.org/t/web-julia-roadmap-assessment/24157)

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**Author:** [@Nosferican](https://discourse.julialang.org/u/Nosferican)\
**Replies:** 1\
**Last updated:** [May 13, 2019, 8:45am UTC](https://discourse.julialang.org/t/web-julia-roadmap-assessment/24157 "2019-05-13T08:45:22Z")

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I wanted to consult the status of some web related functionality in the Julia ecosystem. For HTTP: HTTP.jl For HTML parser: Gumbo.jl Potentially related: Interact.jl Reactive.jl Not entirely sure, Genie Framewo…

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## [Relative path to file](https://discourse.julialang.org/t/relative-path-to-file/24114)

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**Author:** [@dg.aragones](https://discourse.julialang.org/u/dg.aragones)\
**Replies:** 4\
**Last updated:** [May 12, 2019, 10:52pm UTC](https://discourse.julialang.org/t/relative-path-to-file/24114 "2019-05-12T22:52:03Z")

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I’m working in a model with Julia that extracts some data from a spreadsheet. Everything works fine, but I’d like to read the spreadsheet into Julia using a relative path, to be able to run the Julia file from different …

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## [How to call C++ member function in julia?](https://discourse.julialang.org/t/how-to-call-c-member-function-in-julia/24104)

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**Author:** [@alligatorme](https://discourse.julialang.org/u/alligatorme)\
**Replies:** 5\
**Last updated:** [May 12, 2019, 9:29pm UTC](https://discourse.julialang.org/t/how-to-call-c-member-function-in-julia/24104 "2019-05-12T21:29:47Z")

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by using ccall and function address, the global function in C++ can be called. But how about member function? Calling member function needs the function pointer and object reference both, it seems that ccall cannot make …

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## [Interpreting @trace dynamic dispatch warning on apply\_type](https://discourse.julialang.org/t/interpreting-trace-dynamic-dispatch-warning-on-apply-type/24138)

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**Author:** [@venuur](https://discourse.julialang.org/u/venuur)\
**Replies:** 2\
**Last updated:** [May 12, 2019, 9:16pm UTC](https://discourse.julialang.org/t/interpreting-trace-dynamic-dispatch-warning-on-apply-type/24138 "2019-05-12T21:16:25Z")

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New to Julia, and I am trying to build good habits for writing functions. To that end I am applying the Traceur.trace macro to some of my functions and seeing what happens. Here’s an example I don’t understand. When I ru…

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## [How call to value of Windows vars from Julia?](https://discourse.julialang.org/t/how-call-to-value-of-windows-vars-from-julia/24137)

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**Author:** [@programista](https://discourse.julialang.org/u/programista)\
**Replies:** 4\
**Last updated:** [May 12, 2019, 9:14pm UTC](https://discourse.julialang.org/t/how-call-to-value-of-windows-vars-from-julia/24137 "2019-05-12T21:14:07Z")

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I try working with \*.bat and \*exe file in window from Julia level. Is file vol.bat with: cmd vol inside. I am trying get value of number HD to some julia variable julia\> myc=\`vol.bat\` \`vol.bat\` julia\> x=run(myc) C…

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## [(SOLVED) Update Widget Text/Values on Action](https://discourse.julialang.org/t/solved-update-widget-text-values-on-action/24146)

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**Author:** [@anon92994695](https://discourse.julialang.org/u/anon92994695)\
**Replies:** 2\
**Last updated:** [May 12, 2019, 7:20pm UTC](https://discourse.julialang.org/t/solved-update-widget-text-values-on-action/24146 "2019-05-12T19:20:42Z")

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Hey all I’ve been trying to use Julias on board UI for a few things. I’m having a hard time getting things the way I want them. Totally fine with making buttons, and having them do tasks on observables, everythings good …

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## [JuliaDB Footer Line Skips](https://discourse.julialang.org/t/juliadb-footer-line-skips/24132)

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**Author:** [@jekyllstein](https://discourse.julialang.org/u/jekyllstein)\
**Replies:** 0\
**Last updated:** [May 12, 2019, 6:31am UTC](https://discourse.julialang.org/t/juliadb-footer-line-skips/24132 "2019-05-12T06:31:09Z")

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The CSV package has an option in CSV.File() to skip parsing lines at the end of a file, called “footerskip”. The loadtable function in JuliaDB has a keyword argument to skip rows at the beginning of a file (skiplines\_be…

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## [What can cause significantly different performance for pisum microbenchmark on different workstations](https://discourse.julialang.org/t/what-can-cause-significantly-different-performance-for-pisum-microbenchmark-on-different-workstations/23256)

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**Author:** [@adityam](https://discourse.julialang.org/u/adityam)\
**Replies:** 11\
**Last updated:** [May 12, 2019, 1:37am UTC](https://discourse.julialang.org/t/what-can-cause-significantly-different-performance-for-pisum-microbenchmark-on-different-workstations/23256 "2019-05-12T01:37:57Z")

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I am trying to understand what factors impact the performance of Julia code on different hardware. I have two workstations: WS1 is a three old old compute server and WS2 is a two year old desktop, both of which have comp…

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## [Type Diagrams (like UML Class Diagrams for OOPs)](https://discourse.julialang.org/t/type-diagrams-like-uml-class-diagrams-for-oops/10378)

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**Author:** [@rakeshvar](https://discourse.julialang.org/u/rakeshvar)\
**Replies:** 1\
**Last updated:** [May 11, 2019, 10:03pm UTC](https://discourse.julialang.org/t/type-diagrams-like-uml-class-diagrams-for-oops/10378 "2019-05-11T22:03:53Z")

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I am developing a moderately complicated system in Julia. There will be a lot of modules that can be plugged in and off; various combinations of these modules will result in various algorithms. The modules are mostly typ…

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## [Precompile only available in REPL mode?](https://discourse.julialang.org/t/precompile-only-available-in-repl-mode/24115)

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**Author:** [@SPV](https://discourse.julialang.org/u/SPV)\
**Replies:** 3\
**Last updated:** [May 11, 2019, 8:05pm UTC](https://discourse.julialang.org/t/precompile-only-available-in-repl-mode/24115 "2019-05-11T20:05:28Z")

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I can do (v1.0) pkg\> precompile Precompiling project... Precompiling IJulia \[ Info: Recompiling stale cache file /Users/sivapvarma/.julia/compiled/v1.0/IJulia/nfu7T.ji for IJulia \[7073ff75-c697-5162-941a-fcdaad2a7d2a\] P…

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## [Unitful docs have diappeared](https://discourse.julialang.org/t/unitful-docs-have-diappeared/24093)

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**Author:** [@OvidiusCicero](https://discourse.julialang.org/u/OvidiusCicero)\
**Replies:** 5\
**Last updated:** [May 11, 2019, 8:09pm UTC](https://discourse.julialang.org/t/unitful-docs-have-diappeared/24093 "2019-05-11T20:09:05Z")

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There is a very useful package Unitful that I use infrequently. https://github.com/PainterQubits/Unitful.jl Thing is that the README links to https://ajkeller34.github.io/Unitful.jl/stable which seemingly disappeared b…

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## ["Composing" functions](https://discourse.julialang.org/t/composing-functions/24096)

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**Author:** [@asprionj](https://discourse.julialang.org/u/asprionj)\
**Replies:** 1\
**Last updated:** [May 11, 2019, 12:06am UTC](https://discourse.julialang.org/t/composing-functions/24096 "2019-05-11T00:06:32Z")

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Hi, I’m in a situation where I have to assemble an overall function from many other functions. I’m using code generation to create the overall function, so it does not really matter whether the implementation is “nice an…

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## [How execute in Julia this string? eval(Meta.parse()) not works](https://discourse.julialang.org/t/how-execute-in-julia-this-string-eval-meta-parse-not-works/24087)

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**Author:** [@programista](https://discourse.julialang.org/u/programista)\
**Replies:** 1\
**Last updated:** [May 10, 2019, 6:30pm UTC](https://discourse.julialang.org/t/how-execute-in-julia-this-string-eval-meta-parse-not-works/24087 "2019-05-10T18:30:39Z")

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I have some code for julia from another aplication but is with some trash… julia\> output "a=rand(2,2)\\r\\nprintln(a)\\r\\nprintln(\\"podporogram wykonany\\")\\r\\nusing DelimitedFiles\\r\\nwritedlm(\\"a.dat\\",a, '\\\\t');;;;;;;;" …

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## [Dates.value() applied to a list](https://discourse.julialang.org/t/dates-value-applied-to-a-list/24080)

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**Author:** [@dg.aragones](https://discourse.julialang.org/u/dg.aragones)\
**Replies:** 1\
**Last updated:** [May 10, 2019, 3:59pm UTC](https://discourse.julialang.org/t/dates-value-applied-to-a-list/24080 "2019-05-10T15:59:09Z")

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I have a list of dates in the form: t=\[2006-06-01,2006-06-02,2006-06-03\] And I want to apply the function Dates.value() to it. It works well for a single value, however, for a list like the one shown I get an error: E…

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## [Build error on MacOS 10.12 with recent master (BinaryBuilder dependency issues?)](https://discourse.julialang.org/t/build-error-on-macos-10-12-with-recent-master-binarybuilder-dependency-issues/24031)

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**Author:** [@jgoldfar](https://discourse.julialang.org/u/jgoldfar)\
**Replies:** 3\
**Last updated:** [May 9, 2019, 2:40pm UTC](https://discourse.julialang.org/t/build-error-on-macos-10-12-with-recent-master-binarybuilder-dependency-issues/24031 "2019-05-09T14:40:17Z")

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With a clean installation of a recent git clone, I’m unable to make it past the following error: Traceback (most recent call last): File "/Users/jgoldfar/Public/julia-dev/contrib/normalize\_triplet.py", line 118, in \<m…

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## [Sequential peakflops](https://discourse.julialang.org/t/sequential-peakflops/24066)

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**Author:** [@LaurentPlagne](https://discourse.julialang.org/u/LaurentPlagne)\
**Replies:** 2\
**Last updated:** [May 10, 2019, 2:36pm UTC](https://discourse.julialang.org/t/sequential-peakflops/24066 "2019-05-10T14:36:07Z")

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Hi Julians, When I use peakflops(8000;parallel=false) I obtain 1.266034664857239e11 which corresponds to (IMHO) the multicore peak perf of my PC. In addition I see top reaching 800%. The parallel flag seems to be …

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## [Parallel computing, sharing data with all workers](https://discourse.julialang.org/t/parallel-computing-sharing-data-with-all-workers/23907)

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**Author:** [@bernhard](https://discourse.julialang.org/u/bernhard)\
**Replies:** 3\
**Last updated:** [May 10, 2019, 1:40pm UTC](https://discourse.julialang.org/t/parallel-computing-sharing-data-with-all-workers/23907 "2019-05-10T13:40:18Z")

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How can I make some data (e.g. an array or a dataframe) available to all data? I tried using ParallelDatatrasfer.jl but that is not working (see my issue here https://github.com/ChrisRackauckas/ParallelDataTransfer.jl/i…

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## [Error installing XLSX package](https://discourse.julialang.org/t/error-installing-xlsx-package/24070)

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**Author:** [@dg.aragones](https://discourse.julialang.org/u/dg.aragones)\
**Replies:** 1\
**Last updated:** [May 10, 2019, 12:22pm UTC](https://discourse.julialang.org/t/error-installing-xlsx-package/24070 "2019-05-10T12:22:59Z")

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I’m trying to install the XLSX package into Julia to be able to import data from a spreadsheet. However, when I use the command Pkg.add("XLSX") I get the following error: ERROR: Unsatisfiable requirements detectedfor p…

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## [Using + updating packages locals](https://discourse.julialang.org/t/using-updating-packages-locals/24065)

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**Author:** [@pistacliffcho](https://discourse.julialang.org/u/pistacliffcho)\
**Replies:** 3\
**Last updated:** [May 10, 2019, 11:25am UTC](https://discourse.julialang.org/t/using-updating-packages-locals/24065 "2019-05-10T11:25:14Z")

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I’m currently developing a package. At the same time, I’d like to use the package at various different locations on my machine, i.e., in Documents\\badData\\analyzeBadData.jl, I’d like to be using MyPackage and in Document…

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## [How to avoid allocation when modifying a structure in a function](https://discourse.julialang.org/t/how-to-avoid-allocation-when-modifying-a-structure-in-a-function/24062)

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**Author:** [@flibe](https://discourse.julialang.org/u/flibe)\
**Replies:** 2\
**Last updated:** [May 10, 2019, 9:03am UTC](https://discourse.julialang.org/t/how-to-avoid-allocation-when-modifying-a-structure-in-a-function/24062 "2019-05-10T09:03:51Z")

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Dear All I have a function which I need to make as efficient as possible. The function takes many many inputs, and I have organised them into a structure in order to make the code more manageble and clean. I have noti…

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## [Convert a (numerically) non-pd matrix into pd matrix](https://discourse.julialang.org/t/convert-a-numerically-non-pd-matrix-into-pd-matrix/24059)

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**Author:** [@Mr.Robot](https://discourse.julialang.org/u/Mr.Robot)\
**Replies:** 2\
**Last updated:** [May 10, 2019, 8:49am UTC](https://discourse.julialang.org/t/convert-a-numerically-non-pd-matrix-into-pd-matrix/24059 "2019-05-10T08:49:37Z")

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Problem I am trying to compute a linear regression model that predicts overall delay of flights with respect to distance, carrier and some other predictors. I decided to use SweepOperator.jl because large number of obser…

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## [Understanding dispatch on types with nested type parameters and covariance](https://discourse.julialang.org/t/understanding-dispatch-on-types-with-nested-type-parameters-and-covariance/24018)

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**Author:** [@oschulz](https://discourse.julialang.org/u/oschulz)\
**Replies:** 8\
**Last updated:** [May 10, 2019, 8:13am UTC](https://discourse.julialang.org/t/understanding-dispatch-on-types-with-nested-type-parameters-and-covariance/24018 "2019-05-10T08:13:34Z")

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I feel it should be obvious, but I can’t figure it out. Why does this work: julia\> function foo(::Type{\<:AbstractArray{\<:Integer}}) julia\> foo(AbstractArray{\<:Signed}) But not this: julia\> function bar(::Type{\<:Abstra…

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## [Is it possible to effectively hide Juli's code?](https://discourse.julialang.org/t/is-it-possible-to-effectively-hide-julis-code/24060)

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**Author:** [@programista](https://discourse.julialang.org/u/programista)\
**Replies:** 1\
**Last updated:** [May 10, 2019, 7:04am UTC](https://discourse.julialang.org/t/is-it-possible-to-effectively-hide-julis-code/24060 "2019-05-10T07:04:45Z")

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Is it possible to effectively hide Juli’s code so that the user can not read it and reproduce it? Paul

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## [Match a string literal via regex](https://discourse.julialang.org/t/match-a-string-literal-via-regex/24002)

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**Author:** [@thautwarm](https://discourse.julialang.org/u/thautwarm)\
**Replies:** 12\
**Last updated:** [May 10, 2019, 3:22am UTC](https://discourse.julialang.org/t/match-a-string-literal-via-regex/24002 "2019-05-10T03:22:28Z")

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Just like '"(\[^\\\\"\]+|\\\\.)\*?"' in Python or "\\G\\"(\[^\\\\\\"\]+|\\\\\\.)\*?\\"" in C#/F#, it could build a regular expression to parse a whole text like "xxxxxxxxxx\\"xxxxxxxxxxxxxx\\"" However things seem not work in Julia. regex…

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## [Redirect stderr/out to IOBuffer()](https://discourse.julialang.org/t/redirect-stderr-out-to-iobuffer/23984)

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**Author:** [@Pbellive](https://discourse.julialang.org/u/Pbellive)\
**Replies:** 6\
**Last updated:** [May 10, 2019, 2:59am UTC](https://discourse.julialang.org/t/redirect-stderr-out-to-iobuffer/23984 "2019-05-10T02:59:59Z")

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I have a Julia script that runs on a remote machine. The main julia process running this script launches local julia worker processes and waits for AMQP messages that contain input data for a computation. The results of …

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