Use node's vm module to run in clean context #55
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As suggested by Joshua Peek in a previous issue. Node's vm module gives
us full control over the globals passed to the context the code is run
in.
In order to do this we store our code as a JS string, wrap it in an IFFE
(to support the `return` symantics we use for all runtimes)
vm.runInNewContext is called with {filename: "(execjs)"} in order to
have the proper filename appear in backtraces. Normally this string is
inserted into backtraces via a gsub in external_runtime.rb which
replaces the filename.
See https://nodejs.org/api/vm.html
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This is unfortunate. It seems that this hits an issue with node 0.10 where it does not show line numbers for syntax errors when using the |
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I don't think we should care about node 0.10 since it will be stop receiving updates in a couple of weeks: https://github.com/nodejs/LTS#lts-schedule |
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I did some manual bisecting between node versions. It seems like Node 0.11.12 is the first version for which syntax errors inside of The unfortunate thing is that widely used ubuntu versions, precise (12.04) and trusty (14.04), still ship with old node versions (this is what our travis workers are using). However, the breakage here is pretty minor. The only issue is that syntax errors don't include the correct stacktrace. Maybe that is an acceptable compromise for these old node versions. |
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@jhawthorn not sure why but according to Travis tests are passing fine in Node v0.10 (linux) and failing with Node 6.0.0 (osx). I updated the .travis.yml to display the version of Node used. |
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This really would be a fantastic improvement. I just used ExecJS for something and was baffled to get a fresh environment each time. |
As suggested by Joshua Peek in a previous issue. Node's vm module gives us full control over the globals passed to the context the code is run in.
In order to do this we store our code as a JS string, wrap it in an IFFE (to support the
returnsymantics we use for all runtimes)vm.runInNewContextis called with{filename: "(execjs)"}in order to have the proper filename appear in backtraces. Normally this string is inserted into backtraces via a gsub in external_runtime.rb whichreplaces the filename.
See https://nodejs.org/api/vm.html