Beginners September 2017

beginners@lists.squeakfoundation.org

10 participants
5 discussions

Re: [Newbies] Polymorphic or: with block argument
by Ralph Johnson 18 Sep '17

18 Sep '17

Yes, when the compiler sees exp or: [ ... ] then it assumes that "exp" is a boolean-valued expression and generates code that fails if it isn't. Not all Smalltalk compilers perform this optimization, but it is very common. There are a bunch of methods treated like this, ifTrue:ifFalse: is another. whileTrue: is an interesting slightly different case. The compiler usually optimizes whileTrue: only when both receiver and the argument are blocks. So, you can define whileTrue: in other classes without any problem. -Ralph Johnson On Sun, Sep 10, 2017 at 6:33 AM, Lorenz Köhl <rainbowtwigs(a)gmail.com> wrote: > [image: Boxbe] <https://www.boxbe.com/overview> This message is eligible > for Automatic Cleanup! (rainbowtwigs(a)gmail.com) Add cleanup rule > <https://www.boxbe.com/popup?url=https%3A%2F%2Fwww.boxbe.com%2Fcleanup%3Fkey…> > | More info > <http://blog.boxbe.com/general/boxbe-automatic-cleanup?tc_serial=32680703685…> > > I don't understand why Smalltalk doesn't allow me to have an or: > method that takes a block argument (except on Boolean). For example: > > Set or: 1. ==> MNU as expected. > > Set or: [1]. ==> NonBooleanReceiver exception. > > Set or: [:x | x] ==> Argument has too many arguments > > Is it because the compiler specializes this to boolean when it sees > the or: [ ... ] syntax? Is this a tradeoff made for performance? > > greetings, > Lorenz > > _______________________________________________ > Beginners mailing list > Beginners(a)lists.squeakfoundation.org > http://lists.squeakfoundation.org/mailman/listinfo/beginners > >

3 2

Polymorphic or: with block argument
by Lorenz Köhl 11 Sep '17

11 Sep '17

I don't understand why Smalltalk doesn't allow me to have an or: method that takes a block argument (except on Boolean). For example: Set or: 1. ==> MNU as expected. Set or: [1]. ==> NonBooleanReceiver exception. Set or: [:x | x] ==> Argument has too many arguments Is it because the compiler specializes this to boolean when it sees the or: [ ... ] syntax? Is this a tradeoff made for performance? greetings, Lorenz

4 4

Decomposing Binary Data by CR/LF
by John-Reed Maffeo 10 Sep '17

10 Sep '17

Is there an existing method that will tokenize/chunk(?) data from a file using CR/LF? The use case is to decompose a file into PDF objects defined as strings are strings terminated by CR/LF. (if there is an existing framework/project available, I have not found it, just dead ends :-( I have been exploring in #String and #ByteString and this is all I have found that is close to what I need. "Finds first occurance of #Sting" self findString: ( Character cr asString, Character lf asString). "Breaks at either token value" self findTokens: ( Character cr asString, Character lf asString) I have tried poking around in #MultiByteFileStream, but keep running into errors. If there is no existing method, any suggestions how to write a new one? My naive approach is to scan for CR and then peek for LF keeping track of my pointers and using them to identify the CR/LF delimited substrings; or iterate through contents using #findString: TIA, jrm ----- Image ----- C:\Smalltalk\Squeak5.1-16549-64bit-201608180858-Windows\Squeak5.1-16549-64bit-201608180858-Windows\Squeak5.1-16549-64bit.1.image Squeak5.1 latest update: #16549 Current Change Set: PDFPlayground Image format 68021 (64 bit) Operating System Details ------------------------ Operating System: Windows 7 Professional (Build 7601 Service Pack 1) Registered Owner: T530 Registered Company: SP major version: 1 SP minor version: 0 Suite mask: 100 Product type: 1

5 6

Book morph UI question
by Vaidotas Didžbalis 06 Sep '17

06 Sep '17

Hello, Why 'more controls' button in the Book morph has '3' as its title? regards, Vaidotas

3 3

Re: [Newbies] Decomposing Binary Data by CR/LF - Solved (Sort of)
by John-Reed Maffeo 04 Sep '17

04 Sep '17

It turns out that there is no easy answer to my question. There is no way to chunk a binary file using line ending characters because of the inherent nature of binary data which can contain the line end hex values as part of the stream of arbitrary stream. PDF files contain an xref table to all of the objects in the file. I have managed to create classes in my framework which will extract that data into a usable object which I can use to extract the data. Using "self findTokens: ( Character cr asString, Character lf asString)" is useful in the areas of a PDF file which do not contain binary data, and is necessary because the line end values used in a PDF are dependent on the default values of the operating system the file was created on, Thanks again for your interest in my question. Jrm On Tue, Jul 25, 2017 at 3:00 AM, John-Reed Maffeo <jrmaffeo(a)gmail.com> wrote: > Is there an existing method that will tokenize/chunk(?) data from a file > using CR/LF? The use case is to decompose a file into PDF objects defined > as strings are strings terminated by CR/LF. (if there is an existing > framework/project available, I have not found it, just dead ends :-( > > I have been exploring in #String and #ByteString and this is all I have > found that is close to what I need. > > "Finds first occurance of #Sting" > self findString: ( Character cr asString, Character lf asString). > "Breaks at either token value" > self findTokens: ( Character cr asString, Character lf asString) > > I have tried poking around in #MultiByteFileStream, but keep running into > errors. > > If there is no existing method, any suggestions how to write a new one? My > naive approach is to scan for CR and then peek for LF keeping track of my > pointers and using them to identify the CR/LF delimited substrings; or > iterate through contents using #findString: > > TIA, jrm > > ----- > Image > ----- > C:\Smalltalk\Squeak5.1-16549-64bit-201608180858-Windows\ > Squeak5.1-16549-64bit-201608180858-Windows\Squeak5.1-16549-64bit.1.image > Squeak5.1 > latest update: #16549 > Current Change Set: PDFPlayground > Image format 68021 (64 bit) > > Operating System Details > ------------------------ > Operating System: Windows 7 Professional (Build 7601 Service Pack 1) > Registered Owner: T530 > Registered Company: > SP major version: 1 > SP minor version: 0 > Suite mask: 100 > Product type: 1 > >

1 0

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

Beginners September 2017