Path: utzoo!news-server.csri.toronto.edu!rpi!usc!cs.utexas.edu!uunet!mcsun!unido!laura!huba
From: huba@ls5.informatik.uni-dortmund.de (Hubert Baumeister)
Newsgroups: comp.lang.smalltalk
Subject: Re: PP ST R4 - Date dayOfWeek: neverOnASunday!!
Keywords: bug
Message-ID: <3097@laura.UUCP>
Date: 18 Mar 91 13:06:29 GMT
References: <4992@goanna.cs.rmit.oz.au>
Sender: news@laura.UUCP
Reply-To: huba@ls5.informatik.uni-dortmund.de (Hubert Baumeister)
Organization: University of Dortmund, Germany
Lines: 35

In article <4992@goanna.cs.rmit.oz.au>, pnm@goanna.cs.rmit.oz.au (Paul Menon) writes:
|> hi,
|>   A nasty with PPOWST R4 - Beware of converting #Sunday into a day of
|>   week index.  It gives you 0, not 7.  Maybe because Sunday isn't a
|>   weekday? :-)  And we *should* be working on Saturday, right?
|> 
|>   Here's Date's method for dayOfWeek (class protocol: general inquiries)..
|> 
|> ---------------------------
|> dayOfWeek: dayName 
|> 	"Answer the index in a week, 1 - 7, of the day named dayName.  
|> 	Provide an error notification if no such day exists."
|> 
|> 	1 to: 7 do: [:index | (WeekDayNames at: index)
|> 			= dayName ifTrue: [^index \\ 7]].
|> 	self error: dayName asString , ' is not a day of the week'
|> --------------------------
|> 
|> The "^index \\ 7" above is the trap.  7 mod 7 is 0, not 7.
|> 
|> Should I change this method?

I suppose you should do so and return  index instead of index  \\ 7. The only
place where dayOfWeek:  is used is in Date>previous:

previous: dayName 
	"Answer the previous date whose weekday name is dayName."

	^self subtractDays: 7 + self weekdayIndex - (Date dayOfWeek: dayName) \\ 7

This method works for both the wrong and the correct week index of #Sunday
due to the use of \\ 7 in Date>previous.

Hubert Baumeister
(huba@ls5.informatik.uni-dortmund.de)