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bindSym suffices; no 'bind' for macros anymore

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Araq 2012-08-25 01:34:50 +02:00
commit 9a7f0cd851
9 changed files with 48 additions and 73 deletions
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17
doc/manual.txt
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@ -3154,27 +3154,22 @@ The macro call expands to:
writeln(stdout, x)
Bind in macros
~~~~~~~~~~~~~~
BindSym
~~~~~~~
The above ``debug`` macro relies on the fact that ``write``, ``writeln`` and
``stdout`` are declared in the system module and thus visible in the
instantiating context. There is a way to use bound identifiers
(aka `symbols`:idx) instead of using unbound identifiers. The ``bind``
statement plus the ``bindSym`` builtin can be used for that:
(aka `symbols`:idx) instead of using unbound identifiers. The ``bindSym``
builtin can be used for that:
.. code-block:: nimrod
# to work with Nimrod syntax trees, we need an API that is defined in the
# ``macros`` module:
import macros
macro debug(n: expr): stmt =
# we need to declare the used symbols here:
bind write, writeln, stdout
result = newNimNode(nnkStmtList, n)
# iterate over any argument that is passed to this macro:
for i in 1..n.len-1:
# we can access the bound symbol via 'bindSym':
# we can bind symbols in scope via 'bindSym':
add(result, newCall(bindSym"write", bindSym"stdout", toStrLit(n[i])))
add(result, newCall(bindSym"write", bindSym"stdout", newStrLitNode(": ")))
add(result, newCall(bindSym"writeln", bindSym"stdout", n[i]))
@ -3203,7 +3198,7 @@ The macro call expands to:
writeln(stdout, x)
However, the symbols ``write``, ``writeln`` and ``stdout`` are already bound
and are not looked up again. As the example shows, ``bind`` does work with
and are not looked up again. As the example shows, ``bindSym`` does work with
overloaded symbols implicitely.