Christmas Bird Count history report system

# - - -   H i s t A r g s . _ _ i n i t _ _

    def __init__(self):
        '''Constructor.
        '''
        #-- 1
        if HistArgs.initialized:
            return
        else:
            HistArgs.initialized = True

        #-- 2
        # [ form  :=  the incoming CGI arguments as a cgi.FieldStorage
        #             instance ]
        form = cgi.FieldStorage()

For the logic that retrieves both the first and last year entry values, see Section 54, “yearCheck(): Validate a year number form entry”.

        #-- 3
        # [ if form has a valid regform.FIRST_YEAR_ENTRY value ->
        #     self.firstYear  :=  that value in year-number format
        #   else -> raise ScriptError ]
        self.firstYear = lib.yearCheck(form, regform.FIRST_YEAR_ENTRY,
            "First year number", lib.MIN_YEAR)

        #-- 4
        # [ if form has a valid regform.LAST_YEAR_ENTRY value ->
        #     self.lastYear  :=  that value in year-number format
        #   else -> raise ScriptError ]
        self.lastYear = lib.yearCheck(form, regform.LAST_YEAR_ENTRY,
            "Last year number", lib.MAX_YEAR)

For checkboxes, we receive a value only if the user checked the checkbox. We can test for this by using Python's “in” operator; we don't care about the actual value, just whether or not the dictionary-like FieldStorage instance has that key.

        #-- 5
        # [ if form has a value for field LUMP_SUBSP_CB ->
        #     self.lumpSubsp  :=  True
        #   else ->
        #     self.lumpSubsp  :=  False ]
        self.lumpSubsp = regform.LUMP_SUBSP_CB in form

        #-- 6
        self.nmAlias = regform.NM_ALIAS_CB in form

Because year lumping of columns is selected by two radiobuttons instead of a checkbox (the better to explain the consequences of each choice), we use the FieldStorage.getfirst() method to return the value of the selected radiobutton. If for some reason there is no value for this field, we default to true.

        #-- 7
        # [ if form has a YEAR_LUMP_RADIOS value ->
        #     self.yearLumping  :=  that value as a bool
        #   else ->
        #     self.yearLumping  :=  True ]
        self.yearLumping = bool(int(
            form.getfirst(regform.YEAR_LUMP_RADIOS, 0)))

        #-- 8
        # [ if form has a PDF value ->
        #     self.pdf  :=  True
        #   else ->
        #     self.pdf  :=  False ]
        self.pdf = regform.PDF in form

Last in the control group are the Report on selected circles and Reset buttons. There are two ways that this script is called:

In any case, each value of the LAT_LON element should have the format "ddmm-DDDMM". See Section 10.39, “HistArgs._findLatLons(): Check all lat-lon arguments”.

        #-- 9
        # [ if (form has a key ALL) and
        #   (form has at least one key LAT_LON) and
        #   (the LAT_LON values are valid "ddmm-DDDMM" coordinates) ->
        #      self.latLonList  :=  those coordinates as a list of
        #         ("ddmm", "DDDMM") tuples
        #   else if (form has a key whose name starts with
        #   regform.S_ and ending with valid "ddmm-DDDMM"
        #   coordinates) ->
        #      self.latLonList  :=  a list containing one tuple of
        #      the form ("ddmm", "DDDMM") with that ending
        self.latLonList = self._findLatLons(form)