[Python-Dev] String concatenation (original) (raw)

Simon Cross hodgestar at gmail.com
Sun Aug 3 20:38:33 CEST 2008


On Sun, Aug 3, 2008 at 8:29 PM, Antoine Pitrou <solipsis at pitrou.net> wrote:

In many cases there is no runtime concatenation cost.

def f(): ... return "first" + "second" ... import dis dis.dis(f) 2 0 LOADCONST 3 ('firstsecond') 3 RETURNVALUE

The "many cases" only extends to strings whose combined length is less than 20 characters:

dis.dis(lambda : "1234567890123456789" + "0") 1 0 LOAD_CONST 2 ('12345678901234567890') 3 RETURN_VALUE dis.dis(lambda : "1234567890123456789" + "01") 1 0 LOAD_CONST 0 ('1234567890123456789') 3 LOAD_CONST 1 ('01') 6 BINARY_ADD 7 RETURN_VALUE

Adjacent string concentation works on arbitrary length string constants:

dis.dis(lambda : "12345678901234567890" "12345678901234567890") 1 0 LOAD_CONST 0 ('1234567890123456789012345678901234567890') 3 RETURN_VALUE



More information about the Python-Dev mailing list