Regex-Functions - getting user input

[CalibUser]

Hi,

I am writing a regex-function for the Editor in Callibre that needs to obtain user input. I am new to Python and having searched various websites I found that there seems to be two Python functions for obtaining input from the user:

raw_input()

and

input()

However, when used in Callibre Editor these both give the error message:

EOFError: EOF when reading a line

I assume this is because these two pieces of code are used for the Python command window and do not work in windows.

How can I open a window to obtain user input?

[eschwartz]

I don't think you can access user input from the regex-function mode, as it doesn't spawn a dialog box or other input method.

If you want to get one, I strongly suggest you write a plugin instead.



Why do you need to pass user input in a regex? Shouldn't all the information be inside the matched text?
(And if it isn't, again that means a plugin is a better scope for whatever you may be trying to do.)

[CalibUser]

Thanks for your reply.

Sometimes it is not possible to do an automatic search/replace and manual input is required. An example of this is when PDF files are converted to ePufb files and the conversion process inserts full stops before a lower case letter, eg the. dog. With this type of error, sometimes the full stop needs to be removed and sometimes the character after the full stop needs to be capitalised (there are other responses with this example eg 'the U.S.A. receives its fair share of rain' but I will ignore these for now).

Ideally, a dialog box would be displayed and the user could press a button to select the required replacement term from a list that is offered. This would be fater than editing matched text every time the unwanted 'phrase' was detected.

It is possible to achieve this effect by using a series of message dialog boxes where each replacement 'phrase' is displayed in turn and if the user clicks Yes the matched text is replaced with the appropriate 'phrase' but if No is clicked, another dialog box appears that shows the alternative 'phrase' and the user can click Yes or No to accept/reject this phrase. However, opening a series of dialog boxes is not an ideal solution.

As an intial step to producing a dialog box, I thought that, as an exercise, if I produced a text input box (where the user enters a number to select the replacement 'phrase') then I could build on this to produce a more complex dialog box that listed alternatives and the user could click a button to select the required replacement 'phrase'

However, if this needs a plugin then I will have to learn how to do this.

For anybody who wants to display a dialog box when a regex function runs, the code is shown below.

import win32api

MB_OK = 0x0
MB_OKCXL = 0x01
MB_YESNOCXL = 0x03
MB_YESNO = 0x04
MB_HELP = 0x4000
ICON_EXCLAIM=0x30
ICON_INFO = 0x40
ICON_STOP = 0x10
MB_SYSTEMMODAL=4096


reply=win32api.MessageBox(None,"Text to display","Caption",MB_YESNOCXL|ICON_EXCLAIM)


The variable reply will contain an number that corresponds to the button clicked by the user. If MB_SYSTEMMODAL is OR'd with the MB value then the dialog box opens as a system modal dialog box.

The code to open the dialog box must be placed after the statement:

def replace(match, number, file_name, metadata, dictionaries, data, functions, *args, **kwargs):

as required by Callibre.

[eschwartz]

In such cases, most people around here seem to be content to manually edit each match. I don't know how much time you'd save, or how many buttons you'd end up needing to use but as you wish.

I've never tried opening a dialog box from a regex function, it might work. The input() functions OTOH are not meant to be run in a GUI -- like, ever.

P.S. calibre already knows about Qt dialog boxes, which don't necessitate using platform-dependent code. You have no need to use APIs.

[kovidgoyal]

Since S&R runs in the GUI thread, as you discovered, you can show any GUI you like in your replace function. However, this is accidental and is not really something S&R was designed for, so dont be surprised if it breaks someday.

And as @eschwartz said, you should use Qt dialog boxes, that way your code will work everywhere, something like

from PyQt5.Qt import QInputDialog
from calibre.gui2.tweak_book.boss import get_boss

ok, answer = QInputDialog.getText(get_boss().gui, ...)

See the documentation for QInputDialog for the details

[CalibUser]

Thanks for both your replies.

I will find out about how to use QT - I enjoy coding so it will ne interesting to explore something new.

[EbookMakers]

I am interested in this topic. I have a complex regex-function which tries to correct a common mistake in French ebooks. This regex claims to reliably correct, say, 95% of cases. The corresponding branches of the regex can be executed automatically. There are, however, cases that are undecidable by regex. These cases can only be resolved by user choice.

As this error is frequent, one could imagine adding, for undecidable cases, a branch to the regex executed automatically. When the regex selects in that branch, and hands over to the function, the function might ask the user to decide what to do.

As I am ignorant of Python, I tried to run a little test with a function on the above model:

regex : \b([aà])\b

fonction :

def replace(match, number, file_name, metadata, dictionaries, data, functions, *args, **kwargs):
    from PyQt5.Qt import QInputDialog
    from calibre.gui2.tweak_book.boss import get_boss
    if  match.group(1):
        text, ok = QInputDialog().getText(get_boss().gui, "QInputDialog().getText()", "a ou à")
        if ok and text:
           return "{}".format(text)    
        return "{}".format(match.group(1))

Step by step, this regex-function seems to work as expected.

In automatic mode, when the regex selects something, then the function displays the input window, whatever I click on, the window is displayed again indefinitely. I have to kill ebook-edit.

What's wrong ?

[kovidgoyal]

Regex functions are not meant for interactive use. Create plugins for that. Or have your regex function simply mark the suspect text by surrounding it with some placeholders like ??? and then use the search feature to manually fix after.

[EbookMakers]

Thanks for your answer. I'll do it like this.