R.I.P. Ruby Hash Rocket Syntax 1993-2010

Post by j_baker » Thu, Jan 06, 2011, 3:53 AM UTC

baddox wrote: post #49

SoftwareMaven wrote: post #42

Earlier quoted context omitted.

Slower than my_dict = { "foo": 1, "baz": 2 } I was unaware that there was a difference in performance, but a quick timing check shows that it takes about twice as long to create a dictionary with 7 items using dict() than using {}. It makes sense when I stop to think about what the code would have to do, though.

You're right; I'm seeing dict() with explicit kwargs taking 3 times as long as a literal. My unscientific and non-rigorous benchmarks tell me that the construction and unpacking of the kwargs in the dict() call are the cause of most of the slowdown. With the time it takes to assign with a literal normalized to 1, I'm seeing dict( kwargs) (with kwargs created before the benchmark) take 2 and dict(key_1=val_1, key_2=va…

    >>> def dict1():
    ...     {"a" : 1, "b" : 2}
    ... 
    >>> from dis import dis
    >>> dis(dict1)
      2           0 BUILD_MAP                2
                  3 LOAD_CONST               1 (1)
                  6 LOAD_CONST               2 ('a')
                  9 STORE_MAP           
                 10 LOAD_CONST               3 (2)
                 13 LOAD_CONST               4 ('b')
                 16 STORE_MAP           
                 17 POP_TOP             
                 18 LOAD_CONST               0 (None)
                 21 RETURN_VALUE        
    >>> def dict2():
    ...     dict(a=1, b=2)
    ... 
    >>> dis(dict2)
      2           0 LOAD_GLOBAL              0 (dict)
                  3 LOAD_CONST               1 ('a')
                  6 LOAD_CONST               2 (1)
                  9 LOAD_CONST               3 ('b')
                 12 LOAD_CONST               4 (2)
                 15 CALL_FUNCTION          512
                 18 POP_TOP             
                 19 LOAD_CONST               0 (None)
                 22 RETURN_VALUE        

Post by akavlie » Thu, Jan 06, 2011, 4:02 AM UTC

postfuturist wrote: post #45

akavlie wrote: post #28

Earlier quoted context omitted.

Yep, array() is the icing on the cake. Why is the most common data structure in the language instantiated with a function? I could probably rant on PHP syntax all day long, but it's too off topic here.

array() isn't a function, it's just PHP array literal syntax. $x = array("a" => 100); // legal $y = my_func("a" => 100); // illegal

Post by sjs » Thu, Jan 06, 2011, 4:31 AM UTC

prodigal_erik wrote: post #55

postfuturist wrote: post #45

Earlier quoted context omitted.

array() isn't a function, it's just PHP array literal syntax. $x = array("a" => 100); // legal $y = my_func("a" => 100); // illegal

Yeah, call_user_func('strlen', 'hello world') works but call_user_func('array', 'hello world') does not. But for ugly syntax, it's hard to beat the $ sigil being required everywhere for no reason at all (unlike Perl where it actually did something).

Post by astrodust » Thu, Jan 06, 2011, 4:41 AM UTC

obiefernandez wrote: post #24

In related news, Hashrocket (the consultancy) is alive and well, with no intentions of changing our name to Hashcolon. http://hashrocket.com/ In fact, like almost everyone else in our space we're looking to hire => http://hashrocket.com/jobs

Post by cma » Thu, Jan 06, 2011, 5:08 AM UTC

j_baker wrote: post #52

baddox wrote: post #49

Earlier quoted context omitted.

You're right; I'm seeing dict() with explicit kwargs taking 3 times as long as a literal. My unscientific and non-rigorous benchmarks tell me that the construction and unpacking of the kwargs in the dict() call are the cause of most of the slowdown. With the time it takes to assign with a literal normalized to 1, I'm seeing dict( kwargs) (with kwargs created before the benchmark) take 2 and dict(key_1=val_1, key_2=va…

Unpacking kwargs is pretty much equivalent to building a dict. The major slowdown is 1) looking up dict and 2) calling a function: >>> def dict1(): ... {"a" : 1, "b" : 2} ... >>> from dis import dis >>> dis(dict1) 2 0 BUILD_MAP 2 3 LOAD_CONST 1 (1) 6 LOAD_CONST 2 ('a') 9 STORE_MAP 10 LOAD_CONST 3 (2) 13 LOAD_CONST 4 ('b') 16 STORE_MAP 17 POP_TOP 18 LOAD_CONST 0 (None) 21 RETURN_VALUE >>> def dict2(): ... dict(a=1, b=…