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implemented optional pragma for implicit discard

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Araq
2011-09-24 13:55:24 +02:00
parent 033e3dfc50
commit 72ceda98cb
11 changed files with 53 additions and 21 deletions
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22
doc/manual.txt
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@@ -1474,14 +1474,26 @@ Syntax::
Example:
.. code-block:: nimrod
proc p(x, y: int): int {.optional.} =
return x + y
discard proc_call("arg1", "arg2") # discard the return value of `proc_call`
discard p(3, 4) # discard the return value of `p`
The `discard`:idx: statement evaluates its expression for side-effects and
throws the expression's resulting value away. If the expression has no
side-effects, this generates a static error. Ignoring the return value of a
procedure without using a discard statement is a static error too.
throws the expression's resulting value away.
Ignoring the return value of a procedure without using a discard statement is
a static error.
The return value can be ignored implicitely if the called proc/iterator has
been declared with the `optional`:idx: pragma:
.. code-block:: nimrod
proc p(x, y: int): int {.optional.} =
return x + y
p(3, 4) # now valid
Var statement
~~~~~~~~~~~~~