On Wed, Dec 9, 2015 at 3:05 PM, <vish...@stanford.edu> wrote: > Interesting. I didn't think to use dump to check differences. > > Another followup question. After using dump on some simple if statements, > I've noticed that all blocks induce this LineNumberNode which is messing up > the equality. > Is there a way to ignore these nodes in the equality check? They show up in > any kind of block statement (function, if, etc) >
May I ask what do you need the equality of expressions for? It doesn't sound like a too useful concept. There can be expressions that are equal but have different side effects due to the variables they capture (try constructing `Expr(:call, :push!, [1, 2], 1)` twice and eval/compare them). There can also be expressions that are equivalant but appears differently. In general, I never find `==` of expressions too useful. When processing it, you can just ignore the line number nodes if you don't care too much about debug info (also see base/docs/Docs.jl for some example of stripping unwanted part from a expression). There's also MacroTools.jl which provides a nice way to process expressions. > eg: > > dump(:(if true 1 else 0 end)) > > Expr > > head: Symbol if > > args: Array(Any,(3,)) > > 1: Bool true > > 2: Expr > > head: Symbol block > > args: Array(Any,(2,)) > > 1: LineNumberNode > > file: Symbol none > > line: Int64 1 > > 2: Int64 1 > > typ: Any > > 3: Expr > > head: Symbol block > > args: Array(Any,(2,)) > > 1: LineNumberNode > > file: Symbol none > > line: Int64 1 > > 2: Int64 0 > > typ: Any > > typ: Any > > > dump(Expr(:if, true, Expr(:block, 0), Expr(:block,1))) > > Expr > > head: Symbol if > > args: Array(Any,(3,)) > > 1: Bool true > > 2: Expr > > head: Symbol block > > args: Array(Any,(1,)) > > 1: Int64 0 > > typ: Any > > 3: Expr > > head: Symbol block > > args: Array(Any,(1,)) > > 1: Int64 1 > > typ: Any > > typ: Any > > > They're the same minus LineNumberNodes, because block type expressions > always create those things. > > > On Wednesday, December 9, 2015 at 7:21:55 AM UTC-8, STAR0SS wrote: >> >> You can also use dump() on your expressions to see how they differ >> exactly. The normal printing doesn't really show you much.
