Re: How do you pass code blocks to when compiles?

[gemath]

> My intention was to check to see if a proc hello exists in the current scope 
> that doesn't conflict with the proc I'm about to create.

A simple test call to the proc would do (`when compiles(hello()): ...`). But 
then, the compiler would issue an error anyway if there's a conflict with an 
existing proc, so why bother checking that in custom compile-time code?

Re: How do you pass code blocks to when compiles?

[solo989]

My intention was to check to see if a proc hello exists in the current scope 
that doesn't conflict with the proc I'm about to create. If there is a better 
way to check to see if a proc already exists that conflicts I'm open to 
suggestions. The macro way of doing it seems to work as you pass a 
nnkStmtListExpr.newTree into it. I was just wondering if there was a nicer way 
to do it without generating a bunch of NimNodes.

Re: How do you pass code blocks to when compiles?

[GULPF]

The cleanest way is to wrap it in a `block: ...` expression: 


when compiles((block:
echo "test 1"
echo "test 2")):
discard


Run

Re: How do you pass code blocks to when compiles?

[def]

By making it anonymous and calling the proc you define:


import macros
when compiles((proc() =
  echo "hi"
  echo "foo"
  echo "bar")()):
  proc hello() = echo "hi"


Run

How do you pass code blocks to when compiles?

[solo989]

This doesn't seem to work. 


when compiles(proc hello() = echo "hi"):
  proc hello() = echo "hi"


Run

but passing the code into a macro does. 


import macros
macro tester(): untyped =
  let procDef = nnkProcDef.newTree(
ident("hello"),
newEmptyNode(),
newEmptyNode(),
nnkFormalParams.newTree(
  newEmptyNode()
),
newEmptyNode(),
newEmptyNode(),
nnkStmtList.newTree(
  nnkCommand.newTree(
newIdentNode("echo"),
newLit("hi")
  )
)
  )
  var whenStmt = nnkWhenStmt.newTree(
nnkElifBranch.newTree(
  nnkCall.newTree(
newIdentNode("compiles"),
nnkStmtListExpr.newTree(procDef)
  )
)
  )
  #treeRepr looks identical to the quote do version
  #but it will fail
  var whenStmt2 = nnkWhenStmt.newTree(
nnkElifBranch.newTree(
  nnkCall.newTree(
newIdentNode("compiles"),
nnkStmtListExpr.newTree(procDef)
  ),
  newStmtList(procDef,nnkCommand.newTree(ident"echo",newLit("bye")))
)
  )
  whenStmt[0].add quote do:
proc hello() =
  echo "hi"
echo "bye"
  #result = newStmtList(procDef)
  result = newStmtList(whenStmt)
  echo treeRepr result
  echo repr result
  echo treeRepr whenStmt2

tester()
hello()


Run

oddly enough if you use whenStmt2 instead of the quote do version proc hello 
won't exist so that's another problem altogether