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usingmodule()! Who would have guessed!
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@staticfloat
staticfloat committed Jul 17, 2013
1 parent e5101d2 commit 16f5086
Showing 1 changed file with 8 additions and 9 deletions.
17 changes: 8 additions & 9 deletions test/perf/perfutil.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -2,15 +2,14 @@ const ntrials = 5
print_output = isempty(ARGS)
codespeed = length(ARGS) > 0 && ARGS[1] == "codespeed"

try
Pkg.init()
Pkg.add("JSON")
Pkg.add("Curl")
end

if( codespeed )
using JSON
using Curl
if codespeed
try
Pkg.init()
Pkg.add("JSON")
Pkg.add("Curl")
end
usingmodule("JSON")
usingmodule("Curl")

# Ensure that we've got the environment variables we want:
if !haskey(ENV, "JULIA_FLAVOR")
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9 comments on commit 16f5086

@JeffBezanson
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Oh dear. I wish usingmodule didn't have to exist.

@staticfloat
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Is this a syntax parsing issue? I must admit, I was a little surprised by this

@timholy
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It was based on a PR that sat for many months, and only ever got upvotes. So eventually I decided to pull the trigger.

@staticfloat
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Ah, is this because using inside an if statement would be evaluated in the scope of the if block? I guess I'm still not sure why a using directive in nested scope would throw an error, though.....

@JeffBezanson
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Originally I wanted using to be a more static thing, making it easier to deal with cases like #3648 . But since this workaround exists anyway, there's no point, and I might as well allow using inside an if. I guess it is ok as long as the using happens at load time, since we can't change global bindings arbitrarily after that point.

@staticfloat
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So what happens if someone tries to do exactly that? e.g. uses the usingmodule() trick in the middle of running some huge piece of code?

@JeffBezanson
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It's not a disaster, but (1) it affects the dynamically current module (likely Main) rather than the module the call appears in, which is probably not what you want, and (2) it's not clear which bindings will be affected, since most global variables you're using will probably be resolved already, but perhaps not all, and those remaining ones could resovle differently as a result of the usingmodule.

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I see. Is this roughly the same problem as #265, only generalized beyond functions to just generic symbols? (I suppose I'm assuming resolve(symbol) ~== compile(function))

@JeffBezanson
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Yes, it is similar, but not as serious since we simply don't allow changing how global bindings resolve, while we do allow changing method tables.

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