Ben,
I tried to avoid #isString and #isSymbol and I thought it was clear that
#assert:equals: used #= but I agree that I could be more explicit. Here is the
changed version of the unit test (.2 of slice):
testConcatenationIsSymbol
"Concatenating 2 symbols results in another symbol"
self assert: (#foo , #bar) isSymbol.
self assert: (#foo , #bar) == #foobar.
"Concatenating the empty Symbol does not change a Symbol"
self assert: (#foo , emptySymbol) == #foo.
self assert: (emptySymbol , #foo) == #foo.
"Strings and Symbols can still be mixed, the receiver determines the
result type"
"Symbol receiver gives Symbol result"
self assert: (#foo , 'bar') isSymbol.
self assert: (#foo , 'bar') == #foobar.
"String receiver gives String result"
self assert: ('foo' , #bar) isString.
self assert: ('foo' , #bar) = 'foobar'.
"Strings and Symbols still compare content-wise"
self assert: ('foo' , #bar) = #foobar.
"But Strings and Symbols are not identical"
self deny: ('foo' , #bar) == #foobar.
> On 6 Mar 2017, at 15:18, Ben Coman <b...@openinworld.com> wrote:
>
> On Mon, Mar 6, 2017 at 9:21 PM, Sven Van Caekenberghe <s...@stfx.eu> wrote:
>>
>>> On 6 Mar 2017, at 14:12, Ben Coman <b...@openinworld.com> wrote:
>>>
>>>
>>>
>>> On Mon, Mar 6, 2017 at 5:54 PM, Sven Van Caekenberghe <s...@stfx.eu> wrote:
>>> Here is a concrete proposal:
>>>
>>> https://pharo.fogbugz.com/f/cases/19802/Make-sure-Symbol-concatenation-results-in-a-Symbol-not-a-String
>>>
>>> This gives the following assertions:
>>>
>>> "Concatenating 2 symbols results in abother symbol"
>>> self assert: (#foo , #bar) == #foobar.
>>>
>>> "Concatenating the empty symbol does not change a symbol"
>>> self assert: (#foo, emptySymbol) == #foo.
>>> self assert: (emptySymbol, #foo) == #foo.
>>>
>>> "Strings and symbols can still be mixed, the receiver determines the
>>> result type"
>>> "Symbol receiver gives symbol result"
>>> self assert: (#foo , 'bar') == #foobar.
>>> "String receiver gives string result"
>>> self deny: ('foo' , #bar) == #foobar.
>>> self assert: ('foo' , #bar) equals: #foobar.
>>> self assert: ('foo' , #bar) equals: 'foobar'.
>>>
>>>
>>> Those last two seem contradictory.
>>
>> No, Symbols and String can be used interchangeably in Pharo in lots of
>> contexts. Particularly when comparing them, it makes no difference, all the
>> following are/have always been true, independent of this change:
>>
>> #foo = 'foo'
>> 'foo' = #foo
>> #foo = #foo
>> 'foo' = 'foo'
>
> Ah-ha... gotchya. always something more to learn.
>
> So those last three lines a testing that it is a String?
> This meaning is pretty well hidden in the implicit behaviour.
> Why not just...
> self assert: (#foo , 'bar') isString
> which seems to better "says what it means"
>
> If such is poor form in general,
> I'm curious to what degree such rules may be relaxed for unit tests.
> Could it be considered something like premature optimisation
> to make the test too generic?? If isString latter causes a problem later,
> deal with it then.
>
> ====
> On another slightly different point,
> this might be one case where #assert:#equals is less clear than using "="
>
> Its also easy to mis-think the following is contradictory
>>> self deny: ('foo' , #bar) == #foobar.
>>> self assert: ('foo' , #bar) equals: #foobar.
>
> where the alternative here makes the distinction more clear...
> self deny: ('foo' , #bar) == #foobar.
> self assert: ('foo' , #bar) = #foobar.
>
>
> cheers -ben
