[Tutor] switch statements (original) (raw)

Gregor Lingl glingl at aon.at
Fri Jul 9 11:23:11 CEST 2004

Karthikesh Raju schrieb:

Hi All,

We were implementing a switch satetement like testfile.py dec = 1 _perf = { _ _1:bigfile.func1(), _ 2:bigfile.fun2()}[dec] now bigfile.py has def func1(): print "In func1" return 5 def func2(): print "In func2" return 42 Now when we run the testfile.py we get: In func1 In func2

Certainly! You will get a clueon what's going on, if you delete [dec] and have a look at perf: def func1(): print "In func1" return 5

def func2(): print "In func2" return 42

dec = 1 perf = {
1:func1(),
2:func2()}

will output:

In func1 In func2

perf {1: 5, 2: 42}

Clearly perf[1] outputs 5.

What you intended was, that your perf dictionary contains function object. Then you must not evaluate the functions (which is done, if you attach a pair of parentheses) :

dec = 1 perf = {
1:func1,
2:func2}

Look at perf:

perf {1: <function func1 at 0x00A4F2B0>, 2: <function func2 at 0x00A4F270>}

So perf contains two functions. The first one is:

perf[1] <function func1 at 0x00A4F2B0>

You can call it

perf1 In func1 5

To summarize, your program will do what you expected - if I understand you right - , if you change it that way:

testfile.py dec = 1 perf = {
1:bigfile.func1,
2:bigfile.fun2}dec

Regards, Gregor

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