diff options
Diffstat (limited to 'lib/std/with.nim')
| -rw-r--r-- | lib/std/with.nim | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/lib/std/with.nim b/lib/std/with.nim index 79afd61a4..c2eaa4bef 100644 --- a/lib/std/with.nim +++ b/lib/std/with.nim @@ -12,15 +12,16 @@ ## and https://github.com/nim-lang/RFCs/issues/192 for details leading to this ## particular design. ## -## **Since** version 1.2. +## **Since:** version 1.2. -import macros, private / underscored_calls +import std/[macros, private / underscored_calls] macro with*(arg: typed; calls: varargs[untyped]): untyped = - ## This macro provides the `chaining`:idx: of function calls. + ## This macro provides `chaining`:idx: of function calls. ## It does so by patching every call in `calls` to ## use `arg` as the first argument. - ## **This evaluates `arg` multiple times!** + ## + ## .. caution:: This evaluates `arg` multiple times! runnableExamples: var x = "yay" with x: @@ -34,5 +35,14 @@ macro with*(arg: typed; calls: varargs[untyped]): untyped = -= 5 doAssert a == 43 + # Nesting works for object types too! + var foo = (bar: 1, qux: (baz: 2)) + with foo: + bar = 2 + with qux: + baz = 3 + doAssert foo.bar == 2 + doAssert foo.qux.baz == 3 + result = newNimNode(nnkStmtList, arg) underscoredCalls(result, calls, arg) |