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8696 :: What is 'block' in this code

• kcvinu (orginal) [2021-12-08T22:33:32+01:00] view original

  Hi all, I saw this code in Nim manual.

  template t(body: untyped) =
    proc p = echo "hey"
    block:
      body
  
  t:
    p()  # compiles
  Run

  I did some search in manual with the keyword "block" but didn't find any useful hint. What is this block keyword doing here ?

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• sekao (orginal) [2021-12-08T23:11:19+01:00] view original

  It creates a new scope level. I am guessing the point of it is so that variables defined in body will only exist within the t: call, not after it.

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• shirleyquirk (orginal) [2021-12-09T00:03:27+01:00] view original

  this bit of the manual explains named block statements and here in the tutorial deals with scopes and blocks too

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• kcvinu (orginal) [2021-12-10T14:33:55+01:00] view original

  Thanks for the reply.

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• kcvinu (orginal) [2021-12-10T14:38:12+01:00] view original

  Thanks for the reply. When I search with "block" I got this result

  search results NimNodeKind.nnkPragmaBlock RstNodeKind.rnCodeBlock RstNodeKind.rnLineBlock RstNodeKind.rnLiteralBlock RstNodeKind.rnQuotedLiteralBlock htmlgen: blockquote(e: varargs[untyped]): untyped htmlparser: BlockTags threadpool: blockUntil(fv: var FlowVarBaseObj) threadpool: blockUntilAny(flowVars: openArray[FlowVarBase]): int macros: newBlockStmt(body: NimNode): NimNode macros: newBlockStmt(label, body: NimNode): NimNode nativesockets: setBlocking(s: SocketHandle; blocking: bool) NimNodeKind.nnkBlockExpr NimNodeKind.nnkBlockStmt NimNodeKind.nnkBlockType RstNodeKind.rnBlockQuote RstNodeKind.rnLineBlockItem HtmlTag.tagBlockquote winlean: WSAEWOULDBLOCK nativesockets: setInheritable(s: SocketHandle; inheritable: bool): bool dom: Blob

  How can I understand which one is for the "block" keyword ?

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• doofenstein (orginal) [2021-12-10T14:58:26+01:00] view original

  seems like you're looking in the wrong place. It looks like you're searching the standard library, if you want to learn about the core language, look into the manual: https://nim-lang.org/docs/manual.html

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• SolitudeSF (orginal) [2021-12-10T17:16:26+01:00] view original

  the search is for stdlib, not language

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• pietroppeter (orginal) [2021-12-10T17:21:32+01:00] view original

  I also obtain the results reported by @kcvinu if I search "block" in Search input in the Manual. And those results are in fact weird (e.g. dom: Blob has no mention of block anywhere). But to be honest I never use the search input and I always use the browser native search in the page (which in this case would give me the link to Block statement above as first result). I rarely use a search input on other sites too, it gives very often bad results...

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• kcvinu (orginal) [2021-12-10T18:05:04+01:00] view original

  I got same result from the page you mentioned.

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• icedquinn (orginal) [2021-12-11T06:06:57+01:00] view original

  block explicitly creates a new scope similar to putting arbitrary {..}s in C. They can also be named which allows for deep breaks. For example:

  block bagels:
     while true:
        break bagels
     echo "will never be echoed"
  echo "no more bagels"
  Run

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