String concatenation (was: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement?)

[Thomas 'PointedEars' Lahn]

DFS wrote:

> sSQL =  "line 1\n"
> sSQL += "line 2\n"
> sSQL += "line 3"

What is wrong with it in Python is that it is unnecessarily inefficient.  
Python has implicit string concatenation if all operands are string 
literals:

#-----------------------------------------------------------------------
sSQL = ("line 1\n"
        "line 2\n"
        "line 3")
#-----------------------------------------------------------------------

Alternatively, you can join a list of strings:

#-----------------------------------------------------------------------
sSQL = "\n".join([
         "line 1",
         "line 2",
         "line 3",
       ])
#-----------------------------------------------------------------------

Python also has a way that avoids using several string literals:

#-----------------------------------------------------------------------
  sSQL =  """line 1
line 2
line 3"""
#-----------------------------------------------------------------------

or (to have the text aligned)

#-----------------------------------------------------------------------
  sSQL = """\
line 1
line 2
line 3"""
#-----------------------------------------------------------------------

With the “%” string operator (deprecated), str.format(), and str.Template, 
you can use other values in string values even without concatenation.

Next time, RTFM first:

<https://docs.python.org/3.5/tutorial/introduction.html#strings> p.

Finally, with SQL you should prefer Prepared Statements and Stored 
Procedures, not bare strings, to avoid SQL injection:

<https://www.owasp.org/index.php/SQL_Injection_Prevention_Cheat_Sheet>


And if you want to communicate only with a specific person, I strongly 
suggest you send *them* an *e-mail* instead of to the newsgroup/mailing 
list.

Also, it would be a good idea if you posted under your real name.  Internet 
is the thing with cables; Usenet is the thing with people.  I for one tend 
to avoid communicating with few-letter entities; exceptions to that would 
probably include only E.T., M.J., ALF, and K.I.T.T.

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.