Clickable hyperlinks

[Terry Reedy]

On 1/5/2017 12:11 AM, Deborah Swanson wrote:
> Terry Reedy wrote, on January 04, 2017 3:58 PM

>> To have a string interpreted as a clickable link, you send the string
> to
>> software capable of creating a clickable link, plus the information
>> 'this is a clickable link'*.  There are two ways to tag a string as a
>> link.  One is to use markup around the url in the string itself.
>> '<url>' and html are example.  Python provides multiple to make this
>> easy. The other is to tag the string with a separate argument.  Python
>
>> provides tkinter, which wraps tk Text widgets, which have a powerful
> tag
>> system.  One can define a Link tag that will a) cause text to be
>> displayed, for instance, blue and underlined and b) cause clicks on
> the
>> text to generate a web request.  One could then use
>>    mytext.insert('insert', 'http://www.example.com', Link)
>> Browser must do something similar when they encounter when they
>> encounter html link tags.
>
> I've actually moved on from my original question to one of opening a url
> in a browser with python, which seems to be a much more easily achieved
> goal.

> But someone else mentioned tkinter, and I looked at it while ago but
> haven't used it for anything. That really could be the way to go if you
> want to make clickable links, although you still need some kind of
> internet engine to open the url in a browser.

IDLE allows a user to add help menu entries that, when clicked on, open 
either a local file or an internet url.  For instance, adding the pair
'Pillow' and "https://pillow.readthedocs.io/en/latest/" in the Settings 
dialog adda "Pillow" to the help menu (after the standard stuff). 
Clicking on Help => Pillow opens 
"https://pillow.readthedocs.io/en/latest/" in the default browswer. 
IDLE just used the webbrowser module to do this.  No use re-inventing 
the wheel.  If instead "Pillow" were a link in text, the click handler 
should do something similar.

> You say, "There are two ways to tag a string as a link.  One is to use
> markup around the url in the string itself. '<url>' and html are
> examples.  Python provides multiple ways to make this easy."
>
> Can you tell me where I'd begin to look for these? Are they in the core
> language, or in packages?

I was referring to using either % or .format string formatting.  Both 
are in the core and described somewhere in the Library manual.  '%' 
should be in the Symbols page of the Index and 'format' on the 'F' page.

-- 
Terry Jan Reedy