[Nfd-dev] code-style "make incompleteness of split lines obvious" vs chained operations

[Thompson, Jeff]

ndn-cxx already has plenty of code with the first option. This looks good to me. For example:
https://github.com/named-data/ndn-cxx/blob/34a37630a14c67309467074b448057dbf62cda65/src/security/key-chain.cpp#L338


certName.append(signingIdentity)

  .append("KEY")

  .append(keyName.getSubName(signingIdentity.size()))

  .append("ID-CERT")

  .appendVersion();

- Jeff T

From: Junxiao Shi <shijunxiao at email.arizona.edu<mailto:shijunxiao at email.arizona.edu>>
Date: Wednesday, March 11, 2015 at 15:45
To: nfd-dev <nfd-dev at lists.cs.ucla.edu<mailto:nfd-dev at lists.cs.ucla.edu>>
Subject: [Nfd-dev] code-style "make incompleteness of split lines obvious" vs chained operations

Dear folks

Rule 1.12 says:
The incompleteness of split lines must be made obvious.

Split lines occurs when a statement exceed the 80 column limit given above.
It is difficult to give rigid rules for how lines should be split, but the examples above should give a general hint.

In general:

     *   Break after a comma.
     *   Break after an operator.
     *   Align the new line with the beginning of the expression on the previous line.


I'm curious how to format the following snippet: (for this example, let's suppose it doesn't fit in the line width limit)

return QString("%1:%2:%3)
       .arg(localTime->tm_hour, 2, 10, '0')
       .arg(localTime->tm_min, 2, 10, '0')
       .arg(localTime->tm_sec, 2, 10, '0');

Technically ')' is an operator so I can break after it, but this doesn't make the incompleteness obvious.


If I break after the dot operator, the snippet becomes:

return QString("%1:%2:%3).
         arg(localTime->tm_hour, 2, 10, '0').
         arg(localTime->tm_min, 2, 10, '0').
         arg(localTime->tm_sec, 2, 10, '0');

but the bare "arg" in the front doesn't look good.


If I break after the '(' operator, the snippet becomes:

return QString("%1:%2:%3).arg(
         localTime->tm_hour, 2, 10, '0').arg(
         localTime->tm_min, 2, 10, '0').arg(
         localTime->tm_sec, 2, 10, '0');

but this is also weird.


If I break after the comma, the snippet becomes:

return QString("%1:%2:%3).arg(localTime->tm_hour,
                              2, 10, '0').arg(localTime->tm_min,
                                              2, 10, '0').arg(localTime->tm_sec,
                                                              2, 10, '0');

which looks even worse.


Yours, Junxiao
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