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Strings with trailing plus

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  Strings with trailing plus Andrew Poulos <ap_prog@hotmail.com> - 2014-05-05 12:07 +1000
    Re: Strings with trailing plus "Jukka K. Korpela" <jkorpela@cs.tut.fi> - 2014-05-05 08:08 +0300
      Re: Strings with trailing plus Christoph Michael Becker <cmbecker69@arcor.de> - 2014-05-05 13:02 +0200
    Re: Strings with trailing plus Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-05-05 19:45 +0200
    Re: Strings with trailing plus Andrew Poulos <ap_prog@hotmail.com> - 2014-05-09 11:39 +1000
      Re: Strings with trailing plus Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-05-09 10:13 +0200
      Re: Strings with trailing plus Norman Peelman <npeelman@cfl.rr.com> - 2014-05-09 22:43 -0400
    Re: Strings with trailing plus Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-05-09 10:11 +0200
    Re: Strings with trailing plus Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-05-09 12:40 +0100

#24043 — Strings with trailing plus

I typically concatenate long stings with trailing spaces and plus signs eg.

var str = "blah blah... blah " +
           "blah blah... blah " +
           "blah blah... blah " +
           "blah blah... blah " +
           "blah blah... blah";

but I've seen code with leading plus signs and spaces eg.

var str = "blah blah blah"
           + " blah blah... blah"
           + " blah blah... blah"
           + " blah blah... blah"
           + " blah blah... blah";

Is their a reason to prefer one over the other?

Andrew Poulos

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#24044

2014-05-05 5:07, Andrew Poulos wrote:

> I typically concatenate long stings with trailing spaces and plus signs eg.
>
> var str = "blah blah... blah " +
>            "blah blah... blah " +
>            "blah blah... blah " +
>            "blah blah... blah " +
>            "blah blah... blah";
>
> but I've seen code with leading plus signs and spaces eg.
>
> var str = "blah blah blah"
>            + " blah blah... blah"
>            + " blah blah... blah"
>            + " blah blah... blah"
>            + " blah blah... blah";
>
> Is their a reason to prefer one over the other?

This is just a matter of coding style. It may reflect variation in 
writing mathematical expressions: A fairly common practice is to divide 
before an operator in display formulas, but after an operator in text 
formulas.

A “+” sign at the end of a line normally indicates that the expression 
continues on the next line, whereas a “+” sign at the start of a line 
normally indicates that the expression is continuation of something that 
started on the preceding line. In mathematics, people may use “+” both 
at the end of a line and at the start of the next line, for assumed 
clarity, but this is nonstandard and cannot of course be used in 
programming, as it would cause a syntax error. So you have to make your 
choice.

-- 
Yucca, http://www.cs.tut.fi/~jkorpela/

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#24045

Jukka K. Korpela wrote:

> 2014-05-05 5:07, Andrew Poulos wrote:
> 
>> I typically concatenate long stings with trailing spaces and plus
>> signs eg.
>>
>> var str = "blah blah... blah " +
>>            "blah blah... blah " +
>>            "blah blah... blah " +
>>            "blah blah... blah " +
>>            "blah blah... blah";
>>
>> but I've seen code with leading plus signs and spaces eg.
>>
>> var str = "blah blah blah"
>>            + " blah blah... blah"
>>            + " blah blah... blah"
>>            + " blah blah... blah"
>>            + " blah blah... blah";
>>
>> Is their a reason to prefer one over the other?
> 
> This is just a matter of coding style.

ACK.  However, wrt. to ECMAScript implementations one must be aware of
the automatic semicolon insertion (which doesn't apply for the given
examples, though).  Some authors recommend to always break a line
*after* an operator (in the broadest sense) to avoid problems with the ASI.

-- 
Christoph M. Becker

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#24046

Andrew Poulos wrote:

> I typically concatenate long stings with trailing spaces and plus signs
> eg.
> 
> var str = "blah blah... blah " +
>            "blah blah... blah " +
>            "blah blah... blah " +
>            "blah blah... blah " +
>            "blah blah... blah";
> 
> but I've seen code with leading plus signs and spaces eg.
> 
> var str = "blah blah blah"
>            + " blah blah... blah"
>            + " blah blah... blah"
>            + " blah blah... blah"
>            + " blah blah... blah";
> 
> Is their a reason to prefer one over the other?

The reason I prefer the latter over the former is better readability of 
code.  In fact, I prefer

  var str = "blah blah blah"
          + " blah blah... blah"
          + " blah blah... blah"
          + " blah blah... blah"
          + " blah blah... blah";

then (equals and operators aligned), or

  var str = "blah blah blah"
    + " blah blah... blah"
    + " blah blah... blah"
    + " blah blah... blah"
    + " blah blah... blah";

(operators indented one level; depends on the length of the prefix as too 
many leading spaces are wasteful).  Lines can be long even if they do not 
exceed the recommended 80-columns mark, and as I am reading from left to 
right, it is more obvious to me that concatenation (or any other operation) 
occurs if the operator is at the front where it is easily visible.

Another reason is that I can remove lines without having to bother much 
about the operator.  Remove the last line from

  var str = "blah blah blah" +
            " blah blah... blah" +
            " blah blah... blah";

and you get a syntax error or worse:

  var str = "blah blah blah" +
            " blah blah... blah" +

Remove it from

  var str = "blah blah blah"
          + " blah blah... blah"
          + " blah blah... blah";

and you get only a warning about a “missing semicolon”:

  var str = "blah blah blah"
          + " blah blah... blah"

Avoiding to produce syntax errors accidentally is important, and can be very 
important when writing longer complex programs (like libraries) if the code 
is checked as you type (which I prefer).


A reason other people prefer the former over the latter might be that such 
code is easier to write for them.  I have observed, for example, that 
Eclipse JSDT (which I also use) can automatically insert “" + "” when you 
press the Return key while in a string literal.  They also might put greater 
emphasis on the fact that removing the first line from

  var str = "blah blah blah" +
            " blah blah... blah" +
            " blah blah... blah";

does not result in a syntax error, while removing it from

  var str = "blah blah blah"
          + " blah blah... blah"
          + " blah blah... blah";

results in

          + " blah blah... blah"
          + " blah blah... blah";

which in most cases evaluates to NaN (“unary +” operator).

That said, on occasion I prefer a third (or fourth, depending on how you 
count) variant instead:

  var str = [
    "blah blah blah",
    "blah blah... blah",
    "blah blah... blah",
    "blah blah... blah",
    "blah blah... blah"
  ].join(" ");

Particularly so when the glue is not " ", but "\n" or "<br>\n", or there are 
many parts to concatenate.  There are also code efficiency considerations 
here.  It is in general more efficient to build a string consecutively from 
an Array of strings than to built it from consecutive concatenation, because 
no intermediate strings are created.

  var out = [];

  for (var i = 0; i < 10; ++i)
  {
    /* creates one string value */
    out.push("foo " + i + " bar");
  }

  out.join("")

instead of

  var out = "";

  for (var i = 0; i < 10; ++i)
  {
    /* creates two string values */
    out += "foo " + i + " bar";
  }

  out


Knowing other programming languages, I think it is a deficiency of 
ECMAScript that it allows neither to let string literals span lines without 
escape sequence nor supports concatenation of strings without explicit 
operator.  Life could be easier for programmers if code like

  /* as in C++ with string.hpp, or Python */
  var str = "blah blah blah"
            " blah blah... blah"
            " blah blah... blah";

and/or

  /* as in shell scripting, PHP, or Python with triple quotes/apostrophes */
  var str = "blah blah blah
   blah blah... blah
   blah blah... blah";

was syntactically valid (although the latter does not work well with 
indentation; likewise for here-doc.)

Edition 5.1, §7.8.4, finally standardizes

  var str = "blah blah blah\
   blah blah... blah\
   blah blah... blah";

but that is not the same.  Particularly, it is equivalent to the former 
syntax except that it does not work as well with indentation.

-- 
PointedEars
FAQ: <http://PointedEars.de/faq> | SVN: <http://PointedEars.de/wsvn/>
Twitter: @PointedEars2 | ES Matrix: <http://PointedEars.de/es-matrix>
Please do not Cc: me. / Bitte keine Kopien per E-Mail.

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#24049

On 9/05/2014 7:58 AM, Stefan Ram wrote:
> Andrew Poulos <ap_prog@hotmail.com> writes:
>> I typically concatenate long stings with trailing spaces and plus signs eg.
>> var str = "blah blah... blah " +
>>            "blah blah... blah " +
>>            "blah blah... blah " +
>>            "blah blah... blah " +
>>            "blah blah... blah";
>> but I've seen code with leading plus signs and spaces eg.
>> var str = "blah blah blah"
>>            + " blah blah... blah"
>>            + " blah blah... blah"
>>            + " blah blah... blah"
>>            + " blah blah... blah";
>> Is their a reason to prefer one over the other?
>
>    Those are /intermediate/ plus signs in both cases.
>
>    Trailing plus signs would be (not possible in JavaScript):
>
> str = "a"+ "b"+;
>
>    . Preceding plus signs would be:
>
> str = +"a" +"b" /* gives "NaNb" */;
>
>    . But what you have are intermediate plus signs:
>
> str = "a" + "b";

Thanks but I think you misunderstood my question. I wasn't asking about 
how leading or trailing plus signs might affect interpretation but why, 
in a "long" text string that is written over a number of lines, do some 
people prefer plus signs to be leading (or trailing) when concatenating 
the string.

Andrew Poulos

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#24054

Stefan Ram wrote:

> Andrew Poulos <ap_prog@hotmail.com> writes:
>> Thanks but I think you misunderstood my question. I wasn't asking about
>> how leading or trailing plus signs might affect interpretation but why,
>> in a "long" text string that is written over a number of lines, do some
>> people prefer plus signs to be leading (or trailing) when concatenating
>> the string.
> 
>   When JavaScript is being interpreted, it might be most
>   run-time efficient to just write a single long line:

 
> […]
>   Otherwise, I do not indent the following lines, […]

You are still missing the point.

-- 
PointedEars
FAQ: <http://PointedEars.de/faq> | SVN: <http://PointedEars.de/wsvn/>
Twitter: @PointedEars2 | ES Matrix: <http://PointedEars.de/es-matrix>
Please do not Cc: me. / Bitte keine Kopien per E-Mail.

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#24068

On 05/08/2014 09:39 PM, Andrew Poulos wrote:
> On 9/05/2014 7:58 AM, Stefan Ram wrote:
>> Andrew Poulos <ap_prog@hotmail.com> writes:
>>> I typically concatenate long stings with trailing spaces and plus
>>> signs eg.
>>> var str = "blah blah... blah " +
>>>            "blah blah... blah " +
>>>            "blah blah... blah " +
>>>            "blah blah... blah " +
>>>            "blah blah... blah";
>>> but I've seen code with leading plus signs and spaces eg.
>>> var str = "blah blah blah"
>>>            + " blah blah... blah"
>>>            + " blah blah... blah"
>>>            + " blah blah... blah"
>>>            + " blah blah... blah";
>>> Is their a reason to prefer one over the other?
>>
>>    Those are /intermediate/ plus signs in both cases.
>>
>>    Trailing plus signs would be (not possible in JavaScript):
>>
>> str = "a"+ "b"+;
>>
>>    . Preceding plus signs would be:
>>
>> str = +"a" +"b" /* gives "NaNb" */;
>>
>>    . But what you have are intermediate plus signs:
>>
>> str = "a" + "b";
>
> Thanks but I think you misunderstood my question. I wasn't asking about
> how leading or trailing plus signs might affect interpretation but why,
> in a "long" text string that is written over a number of lines, do some
> people prefer plus signs to be leading (or trailing) when concatenating
> the string.
>
> Andrew Poulos
>

   My preference is for preceding such that:

var str = "blah blah... blah"
         + "blah blah... blah"
         + "blah blah... blah"
         + "blah blah... blah"
         + "blah blah... blah";

...the beginnings (+) of each continued line lines up (=) when possible 
(in language of choice). Sometimes even breaking the lines up on visual 
cues for sake of readability. Even in languages where a continuation 
marker is required such that:

var str = "blah blah... blah" _
         + "blah blah... blah" _
         + "blah blah... blah" _
         + "blah blah... blah" _
         + "blah blah... blah"



-- 
Norman
Registered Linux user #461062
-Have you been to www.php.net yet?-

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#24053

Stefan Ram wrote:

> Andrew Poulos <ap_prog@hotmail.com> writes:
>>I typically concatenate long stings with trailing spaces and plus signs
>>eg. var str = "blah blah... blah " +
>>           "blah blah... blah " +
>>           "blah blah... blah " +
>>           "blah blah... blah " +
>>           "blah blah... blah";
>>but I've seen code with leading plus signs and spaces eg.
>>var str = "blah blah blah"
>>           + " blah blah... blah"
>>           + " blah blah... blah"
>>           + " blah blah... blah"
>>           + " blah blah... blah";
>>Is their a reason to prefer one over the other?
> 
>   Those are /intermediate/ plus signs in both cases.
> 
>   Trailing plus signs would be […]

[de] Nuhr.

,<http://www.oxforddictionaries.com/definition/english/trail?q=trailing#trail__16>
| 
| [NO OBJECT] (Typically of a plant) grow or hang over the edge of something 
| or along the ground:

(whereas the edge would be the perceived edge of the source code)

,-<http://www.merriam-webster.com/dictionary/trail>
|
| 3 […]
|   c :  to follow along behind

-- 
PointedEars
FAQ: <http://PointedEars.de/faq> | SVN: <http://PointedEars.de/wsvn/>
Twitter: @PointedEars2 | ES Matrix: <http://PointedEars.de/es-matrix>
Please do not Cc: me. / Bitte keine Kopien per E-Mail.

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#24067

In comp.lang.javascript message <T72dnUGM8ZJAb_vOnZ2dnUVZ_g2dnZ2d@westne
t.com.au>, Mon, 5 May 2014 12:07:56, Andrew Poulos <ap_prog@hotmail.com>
posted:

>I typically concatenate long stings with trailing spaces and plus signs eg.
>
>var str = "blah blah... blah " +
>          "blah blah... blah " +
>          "blah blah... blah " +
>          "blah blah... blah " +
>          "blah blah... blah";
>
>but I've seen code with leading plus signs and spaces eg.
>
>var str = "blah blah blah"
>          + " blah blah... blah"
>          + " blah blah... blah"
>          + " blah blah... blah"
>          + " blah blah... blah";
>
>Is their a reason to prefer one over the other?


Yes.  With a trailing + it is immediately obvious to a human reader of
the line, without looking ahead, that there is a continuation.  That
applies particularly in the case of a single continuing line; with many
continuing lines, the overall structure will be noticed peripherally
while the first line is being considered - if they are on-screen.

JavaScript treats them the same, although there may be a very small
browser-dependent speed difference at the parsing stage.  Obviously you
can measure that well enough to see whether it is significant.


-- 
 (c) John Stockton, Surrey, UK.  ¬@merlyn.demon.co.uk   Turnpike v6.05   MIME.
   Web  <http://www.merlyn.demon.co.uk/> - FAQish topics, acronyms, & links.
 Proper <= 4-line sig. separator as above, a line exactly "-- " (SonOfRFC1036)
 Do not Mail News to me. Before a reply, quote with ">" or "> " (SonOfRFC1036)

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