Throw more meaningful error when calling @bcomp with only one function #8
Description
Currently calling @bcomp with only one function say f as follows @bcomp rand(10) f(_) gives a cryptic error because the length function is being invoked on a Chairmarks.Benchmark object, which is obviously going to fail. The real reason this fails is because @bcomp is meant to be used only when comparing two or more functions.
I think we should catch this behavior and throw an error that says something like @bcomp is for comarping two or more functions. Please use @bs for single function benchmarking. I don't know enough about macros to be able to do that though. Maybe @LilithHafner can help
Here's an example of the error:
julia> @bcomp 500 rand(_)
ERROR: MethodError: no method matching length(::Chairmarks.Benchmark)
The function `length` exists, but no method is defined for this combination of argument types.
Closest candidates are:
length(::Profile.HeapSnapshot.Nodes)
@ Profile ~/.julia/juliaup/julia-1.11.2+0.aarch64.apple.darwin14/share/julia/stdlib/v1.11/Profile/src/heapsnapshot_reassemble.jl:52
length(::Core.SimpleVector)
@ Base essentials.jl:933
length(::LibGit2.GitBlob)
@ LibGit2 ~/.julia/juliaup/julia-1.11.2+0.aarch64.apple.darwin14/share/julia/stdlib/v1.11/LibGit2/src/blob.jl:3
...
Stacktrace:
[1] length(g::Base.Generator{Chairmarks.Benchmark, var"#115#117"})
@ Base ./generator.jl:51
[2] _similar_shape(itr::Base.Generator{Chairmarks.Benchmark, var"#115#117"}, ::Base.HasLength)
@ Base ./array.jl:663
[3] collect(itr::Base.Generator{Chairmarks.Benchmark, var"#115#117"})
@ Base ./array.jl:790
[4] macro expansion
@ ~/projects/julia_repos/PrettyChairmarks.jl/src/PrettyChairmarks.jl:96 [inlined]
[5] top-level scope
@ REPL[22]:1