Python-style catch statement works but is misleading

[LilithHafner]

It is unfortunate that the standard python try-catch style works fine in Julia but silently catches too much

>>> try:
...     foo
... except NameError:
...     print("Got a name error")
... 
Got a name error

julia> try
           foo
       catch NameError
           println("Got a name error")
       end
Got a name error

See JuliaStats/Statistics.jl#147 (comment) for an example of this in the wild (in a stdlib, my fault)

[Seelengrab]

I'm not sure if this behavior is explicitly documented (https://docs.julialang.org/en/v1/manual/control-flow/#Exception-Handling) or not (it certainly "leaks through", but could be more explicit), but a good way to make this "work" automatically could be by supporting something like

try
    foo
catch e::NameError
    println("got a name error: $e")
end

or

try
    foo
catch ::NameError
    println("got a name error")
end

to do the equivalent of

try
    foo
catch e
    e isa NameError || rethrow(e)
    println("got a name error: $e")
end

In the short term though, adding an explicit warning to the docs is probably best.

[KristofferC]

The docs say:

 The syntax `catch e` (where `e` is any variable) assigns the thrown exception object to the given variable within the catch block.

so it is pretty clear what this does. Adding it to the Noteworthy Language differences is probably a good idea though.