Add arguments to callback function for reportlab PageTemplate

Question

I am using the code in this source here to create a sample doc. Particularly, this is the entire working code:

import os
from reportlab.platypus import BaseDocTemplate, Frame, Paragraph, NextPageTemplate, PageBreak, PageTemplate
from reportlab.lib.units import inch
from reportlab.lib.styles import getSampleStyleSheet


styles=getSampleStyleSheet()
Elements=[]

doc = BaseDocTemplate('basedoc.pdf',showBoundary=1)

def foot1(canvas,doc):
    canvas.saveState()
    canvas.setFont('Times-Roman',19)
    canvas.drawString(inch, 0.75 * inch, "Page %d" % doc.page)
    canvas.restoreState()
def foot2(canvas,doc):
    canvas.saveState()
    canvas.setFont('Times-Roman',9)
    canvas.drawString(inch, 0.75 * inch, "Page %d" % doc.page)
    canvas.restoreState()

#normal frame as for SimpleFlowDocument
frameT = Frame(doc.leftMargin, doc.bottomMargin, doc.width, doc.height, id='normal')

#Two Columns
frame1 = Frame(doc.leftMargin, doc.bottomMargin, doc.width/2-6, doc.height, id='col1')
frame2 = Frame(doc.leftMargin+doc.width/2+6, doc.bottomMargin, doc.width/2-6,
               doc.height, id='col2')

Elements.append(Paragraph("Frame one column, "*500,styles['Normal']))
Elements.append(NextPageTemplate('TwoCol'))
Elements.append(PageBreak())
Elements.append(Paragraph("Frame two columns,  "*500,styles['Normal']))
Elements.append(NextPageTemplate('OneCol'))
Elements.append(PageBreak())
Elements.append(Paragraph("Une colonne",styles['Normal']))
doc.addPageTemplates([PageTemplate(id='OneCol',frames=frameT,onPage=foot1),
                      
                      PageTemplate(id='TwoCol',frames=[frame1,frame2],onPage=foot2),
                      ])
#start the construction of the pdf
doc.build(Elements)

Suppose I want to add one extra argument, x_position, to the callback function foot1 to determine the horizontal location of the footer, as following:

def foot1(canvas,doc, x_position):  # x_position is in inch
    canvas.saveState()
    canvas.setFont('Times-Roman',19)
    canvas.drawString(x_position, 0.75 * inch, "Page %d" % doc.page)
    canvas.restoreState()

How would I go about passing this additional argument to the callback foot1 in the flowable class PageTemplate in this line:

doc.addPageTemplates([PageTemplate(id='OneCol',frames=frameT,onPage=foot1),                      
                      PageTemplate(id='TwoCol',frames=[frame1,frame2],onPage=foot2),
                      ])

Answer 1

You can make use of functools partial:

from functools import partial

doc.addPageTemplates([PageTemplate(id='OneCol',frames=frameT,onPage=partial(foot1, x_position=2)),                      
                      PageTemplate(id='TwoCol',frames=[frame1,frame2],onPage=foot2),
                      ])