My solution right now is a macro macro isDefined(x) return :(defined = true; try eval($x); catch e; defined = isa(e,UndefVarError); end; defined) end
I find this to be very clunky, but it works for my limited test cases. > All compile-time undefined bindings become a runtime lookup from the > enclosing (i.e. module) scope. The undefined error means that this lookup > failed. If that is so, what is the function I can call to determine whether my variable is in scope? `isdefined` is definitely _not_ that function. How do I need to call that function from Julia? Your explanation is not a solution to my problem. On Wed, Jul 20, 2016 at 12:01 AM, Yichao Yu <yyc1...@gmail.com> wrote: > On Tue, Jul 19, 2016 at 11:54 PM, Isaiah Norton <isaiah.nor...@gmail.com> > wrote: > > Creating variables dynamically at local scope is not possible (if you are > > calling `eval` inside a function: it does not work like that!) > > > >> Since the runtime can determine that the local variable is undefined as > >> evidenced by an appropriate error > > > > > > All compile-time undefined bindings become a runtime lookup from the > > enclosing (i.e. module) scope. The undefined error means that this lookup > > failed. > > We do have local only variables that can be undefined. > > > > > > > On Tue, Jul 19, 2016 at 10:43 PM, Christopher Rinderspacher > > <crind...@gmail.com> wrote: > >> > >> I, too, would like to be able to check whether local variables are > >> defined. In my case, I am parsing a file that doesn't allow > redefinition of > >> a field. The natural way to do this is to check whether I've previously > >> assigned a variable with the content. > >> > >> The fact that isdefined only looks at the module scope is really > >> irrelevant to my use case. Since the runtime can determine that the > local > >> variable is undefined as evidenced by an appropriate error, I wish I > could > >> do the same within my function without some clunky try ... catch > mehcanism. > > A separate bool flag or a Nullable should work equally well. > > >> > >> > >> On Monday, May 11, 2015 at 7:31:06 PM UTC-4, Juha Heiskala wrote: > >>> > >>> Hello, > >>> > >>> Am I missing something or doesn't isdefined detect local variables of a > >>> function? > >>> > >>> > >>> julia> foo()= begin bar=1; isdefined(current_module(), :bar); end > >>> foo (generic function with 1 method) > >>> > >>> julia> foo() > >>> false > >>> > >>> Best Regards, > >>> > >>> Juha > >>> > >>> julia version 0.3.5 > >>> > >>> julia> versioninfo() > >>> Julia Version 0.3.5 > >>> Commit a05f87b* (2015-01-08 22:33 UTC) > >>> Platform Info: > >>> System: Linux (x86_64-linux-gnu) > >>> CPU: Intel(R) Core(TM) i7-3667U CPU @ 2.00GHz > >>> WORD_SIZE: 64 > >>> BLAS: libopenblas (NO_LAPACK NO_LAPACKE DYNAMIC_ARCH NO_AFFINITY) > >>> LAPACK: liblapack.so.3 > >>> LIBM: libopenlibm > >>> LLVM: libLLVM-3.3 > > > > >
