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Re: st: Why do `test' and a`test' make a difference?


From   Cory Smith <corybsmith@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Why do `test' and a`test' make a difference?
Date   Sun, 10 Feb 2013 23:14:43 -0500

It's getting tripped up by the apostrophe in test since it's a
character with special meaning. Stata kinda sucks with strings...

Try local test "Jephs Example" and it will be more sensical.

On Sun, Feb 10, 2013 at 10:10 PM, Jeph Herrin <stata@spandrel.net> wrote:
> I'd like a systematic account of how word lists are parsed. For instance, I
> have been scratching my head over the output of this:
>
> local test "Jeph's Example"
> local wordA `: word 1 of `test''
> local wordB : word 1 of `test'
> local wordC =`"`:word 1 of `test''"'+"[ ]"+`"`:word 2 of `test''"'
> di "`wordA'"
> di "`wordB'"
> di "`wordC'"
>
> cheers,
> Jeph
>
>
> On 2/10/2013 7:20 PM, Nick Cox wrote:
>>
>> See also
>>
>> http://www.stata.com/support/faqs/programming/backslashes-and-macros/
>>
>> for a systematic account.
>>
>> Nick
>>
>> On Sun, Feb 10, 2013 at 9:24 PM, Dirk Enzmann
>> <dirk.enzmann@uni-hamburg.de> wrote:
>>>
>>> Thank you Nick, very helpful!
>>>
>>> And thanks to Statalist as an institution to turn to when searches such
>>> as
>>> -hsearch backslash-, -hsearch pathname-, -hsearch filename-, -search
>>> escape-
>>> or the subject index of the manual(s) do not help. I suspected an issue
>>> with
>>> escape characters, but didn't know where to look for help besides asking
>>> Statalist.
>>>
>>> With your help I could locate section 18.3.11 in [U] which explicitly
>>> warns
>>> Windows users about not using backslashes in pathnames. However, I still
>>> couldn't locate an explanation of the use of the backslash \ as an escape
>>> character in the manuals.
>>>
>>>
>>> To summarize: Whereas the use of a backslash results in
>>>
>>> ------------------------------------
>>> . global path = "d:\my folder\"
>>> . local test = "pre_"
>>> .
>>> . di "${path}`test'my name.dta"
>>> d:\my folder`test'my name.dta
>>> .
>>> . di "${path}a`test'my name.dta"
>>> d:\my folder\apre_my name.dta
>>> ------------------------------------
>>>
>>> the clean way of using forward slashes, instead, results in
>>>
>>> ------------------------------------
>>> . global path = "d:/my folder/"
>>> . local test = "pre_"
>>> .
>>> . di "${path}`test'my name.dta"
>>> d:/my folder/pre_my name.dta
>>> .
>>> . di "${path}a`test'my name.dta"
>>> d:/my folder/apre_my name.dta
>>> ------------------------------------
>>>
>>> Dirk
>>>
>>>
>>>> In Stata backslashes have two roles
>>>>
>>>> 1. General: As an escape character.
>>>>
>>>> 2. Specific, for Windows users so inclined: As a separator within >
>>>> pathnames.
>>>>
>>>> and single left quotation marks ` also have two roles
>>>>
>>>> 1. As introducing local macro references.
>>>>
>>>> 2. As literal characters, an interpretation you insist on with \`
>>>>
>>>> So
>>>>
>>>> \`test'
>>>>
>>>> is taken as a sign that for some reason for your own you are
>>>> protecting the ` of `test', which is why you put the \ in there.
>>>>
>>>> So, don't do that. Use forward slashes for pathname separators, even
>>>> in Windows. This advice is spelled out in [U] and again in
>>>>
>>>> SJ-8-3  pr0042  . . . . . . .  Stata tip 65: Beware the backstabbing >
>>>> backslash
>>>>          . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . >
>>>> N.
>>>> J. Cox
>>>>          Q3/08   SJ 8(3):446--447                                 (no >
>>>> commands)
>>>>          tip to use forward slash instead of backslash for
>>>>          directory and file names
>>>>
>>>> Nick
>>>>
>>>> On Sun, Feb 10, 2013 at 1:18 PM, Dirk Enzmann
>>>>
>>>>> Why does the backslash as part of the global macro $path vanish (and
>>>>
>>>>
>>>>> `test' is not evaluated as a local macro) when immediately combined
>>>>> with
>>>>> the local macro `test', although it does not vanish (and the content of
>>>>> `test' is displayed) when not immediately combined as shown in the two
>>>>> variants of -di- in the example below?
>>>>>
>>>>> * --- Stata example start: -----------
>>>>>
>>>>> global path = "d:\my folder\"
>>>>> local test = "pre_"
>>>>> di "${path}`test'my name.dta"
>>>>> di "${path}a`test'my name.dta"
>>>>>
>>>>> * --- End Stata example. ------------
>>>>>
>> *
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>>
>>
> *
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*
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