@assert message does not interpolate

[aviks]

julia> versioninfo()
Julia Version 0.3.0-prerelease+695
Commit 47915f3* (2013-12-27 05:27 UTC)
Platform Info:
  System: Darwin (x86_64-apple-darwin11.4.2)
  CPU: Intel(R) Core(TM)2 Duo CPU     L9400  @ 1.86GHz
  WORD_SIZE: 64
  BLAS: libopenblas (USE64BITINT DYNAMIC_ARCH NO_AFFINITY)
  LAPACK: libopenblas
  LIBM: libopenlibm

julia> a=1;b=2
2

julia> @assert a==b "$a not equal $b"
ERROR: assertion failed: :($(Expr(:string, :a, " not equal ", :b)))
 in error at error.jl:21

[JeffBezanson]

I've added support for this, but doing this is not recommended since a lot of extra code has to be generated for constructing the interpolated string. While of course the string itself is only allocated in case of an error, it can still negatively affect surrounding code.

[mbauman]

@JeffBezanson is that negative impact just in terms of compilation time and total code size (cache misses)? Or is there something else that I'm missing? It was one of the first things I tried to do as a beginner myself, so I'm just curious. As long as it's not in library code or a hot-path, it should be fine, yes?

[JeffBezanson]

If the containing function is otherwise very simple, it can cause generation of a GC frame, which can slightly slow down calls to the function.