November 2014 - Pharo-dev - lists.pharo.org

Re: [Pharo-dev] Stream instead of string concatenation

by stepharo

Sven started to write a chapter GoodPractice on PharoForTheEntreprise. If you want to imporve it just go. https://github.com/SquareBracketAssociates/PharoForTheEnterprise-english/tr… Stef !Some Good Coding Practices Best Smalltalk Practices by Kent Beck, Smalltalk by Example and Smalltalk with Style are three excellent books about coding practices. Every Smalltalkers should read them. Still there are some coding practices that programmers should be aware of. In this chapter we present some simple and good practices that make your code often more efficient and avoid generating unnecessary garbage. !!Avoid unnecessary string concatenations In Smalltalk, the message ==,== \mthindex{String}{,} concatenates two strings. It is handy but this message is really costly since it copies the receiver. Therefore avoid it as much as possible and especially in loop since it multiplies the effect. Prefer to use \ct{streamContents:} \mthindex{String}{streamContents:}, ==nextPut:== and ==nextPutAll:== since they avoid the duplication. The message ==streamContents:== expects a block would argument is a stream on the receiver. Let us have a look at the following code snippet. [[[ String streamContents: [:s | #('Pharo''s' 'goal' 'is' 'to' 'deliver' 'a' 'clean,' 'innovative,' 'free' 'open-source' 'Smalltalk' 'environment.' 'By' 'providing' 'a' 'stable' 'and' 'small' 'core' 'system,' 'excellent' 'dev' 'tools,' 'and' 'maintained' 'releases,' 'Pharo' 'is' 'an' 'attractive' 'platform' 'to' 'build' 'and' 'deploy' 'mission' 'critical' 'Smalltalk' 'applications.') do: [:each | s nextPutAll: each; nextPut: Character space]. s contents] ]]] Note that we took an example with many strings to stress the effect, but the bench results shows already a 4 factor. [[[ [String streamContents: [:s | #('Pharo''s' 'goal' 'is' 'to' 'deliver' 'a' 'clean,' 'innovative,' 'free' 'open-source' 'Smalltalk' 'environment.' 'By' 'providing' 'a' 'stable' 'and' 'small' 'core' 'system,' 'excellent' 'dev' 'tools,' 'and' 'maintained' 'releases,' 'Pharo' 'is' 'an' 'attractive' 'platform' 'to' 'build' 'and' 'deploy' 'mission' 'critical' 'Smalltalk' 'applications.') do: [:each | s nextPutAll: each; nextPut: Character space]. s contents]] bench --> '110,000 per second.' [| s| s := ''. #('Pharo''s' 'goal' 'is' 'to' 'deliver' 'a' 'clean,' 'innovative,' 'free' 'open-source' 'Smalltalk' 'environment.' 'By' 'providing' 'a' 'stable' 'and' 'small' 'core' 'system,' 'excellent' 'dev' 'tools,' 'and' 'maintained' 'releases,' 'Pharo' 'is' 'an' 'attractive' 'platform' 'to' 'build' 'and' 'deploy' 'mission' 'critical' 'Smalltalk' 'applications.') do: [:each | s := s , each , Character space asString]. s ] bench --> '31,500 per second.' ]]] Another example that may be a bit draft and fuzzy but gives an idea of the cost that you may gain. [[[ String streamContents: [:s | Smalltalk globals allClasses do: [:each | s nextPutAll: each name]. s contents]] bench --> '246 per second.' | s | s := ''. [Smalltalk globals allClasses do: [:each | s := s, each name]] bench --> '2.01 per second.' ]]] !!!Preallocate when possible. Preallocate when possible the string used with\ct{new:streamContents:}. For example, the following method does not take advantage that the result is always a 8 characters string. [[[ Time>>print24 "Return as 8-digit string 'hh:mm:ss', with leading zeros if needed" ^String streamContents: [ :aStream | self print24: true on: aStream ] ]]] This version does the same but more efficiently, since the system does not have to reallocate the underlying buffer. [[[ Time>>print24 "Return as 8-digit string 'hh:mm:ss', with leading zeros if needed" ^ String new: 8 streamContents: [ :aStream | self print24: true on: aStream ] ]]] !!! Use ==nextPut:== when possible. When you can, use ==nextPut:== use it instead of ==nextPutAll:==. Indeed ==nextPutAll:== requires that the argument is a container of elements. When you have already the element, no need to create an extra container. For example better use the second form. [[[ stream nextPutAll: '0' ]]] [[[ stream nextPut: $0 ]]] !!Avoid creating temporary objects The computation of minute in Time could be written as \ct{asDuration minutes}. However, this solution creates a duration object that is only used to get the minutes. In addition to be slow such approach generates extra garbage which stresses the garbage collector. [[[ Time>>minute ^ self asDuration minutes Time>>asDuration "Answer the duration since midnight" ^ Duration seconds: seconds nanoSeconds: nanos ]]] A much better solution is to use the encapsulation of the class Time and performs the computation locally as [[[ Time>>minute "Answer a number that represents the number of complete minutes in the receiver, after the number of complete hours has been removed." ^ (seconds rem: SecondsInHour) quo: SecondsInMinute ]]] !! Avoid several iterations on the same collection It may seem obvious but it is better to iterate once than two on the same collection, when we can do what we want in a single pass. For example, the following code creates a first string then creates another one where the character ==$:== is removed. [[[ Time>>hhmm24 "Return a string of the form 1123 (for 11:23 am), 2154 (for 9:54 pm), of exactly 4 digits" ^(String streamContents: [ :aStream | self print24: true showSeconds: false on: aStream ]) copyWithout: $: ]]] Better implement it as [[[ Time>>hhmm24 "Return a string of the form 1123 (for 11:23 am), 2154 (for 9:54 pm), of exactly 4 digits" ^ String new: 4 streamContents: [ :aStream | self hour printOn: aStream base: 10 length: 2 padded: true. self minute printOn: aStream base: 10 length: 2 padded: true ] ]]] have a look at: http://www.slideshare.net/esug/design-principlesbehindpatagonia Le 27/11/14 09:22, Max Leske a Ã©crit : >> On 26.11.2014, at 17:32, Ben Coman <btc(a)openInWorld.com> wrote: >> >> Yuriy Tymchuk wrote: >>> Hi everyone! >>> There is a Lint rule that suggests to use stream instead of strings concatenation. What is the most common way, to create a string this way, because the only thing I can come up with is: >>> String streamContents: [ :stream | >>> stream >>> nextPutAll: 'Hello'; >>> nextPut: $ ; >>> nextPutAll: 'Worldâ] >>> But Iâm not sure if it is the preferred solution. >>> Cheers >>> Uko >> This is typical advise, but previous discussion found it to be not necessarily true. >> >> https://www.mail-archive.com/pharo-dev@lists.pharo.org/msg08162.html >> > Very good advice, thanks Ben! > >> Perhaps the rule should be ammended/deleted. > Maybe a metric can be derived from Svenâs observations, e.g. âdonât apply if the strings are constantsâ etc. I donât think the rule should be deleted because in the general case itâs important to understand that streams can be more efficient. > >> cheers -ben >> >> > >

Nov. 27, 2014

Re: [Pharo-dev] [SO] SSL exception with ZnSecureServer

by phil＠highoctane.be

I tried the procedure and it works fine on my Ubuntu 14.04 LTS and Pharo 3.0 Little script with the steps in attach. Server started as follows: (ZnSecureServer on: 1235) certificate: '/home/philippeback/.ssh/server.pem'; logToTranscript; start; yourself. [image: Inline image 1] Cool to have! The Z* things are really awesome and inspiring. Phil On Thu, Nov 27, 2014 at 9:29 AM, Sven Van Caekenberghe <sven(a)stfx.eu> wrote: > I just sent the OP this in reply to a private message ;-) > > > Hi Monty, > > It should work on Linux. This is how I once did it (making the > certificate), more than a year ago (I know that others have managed to do > this too): > > ==== > > sven@netbook:~/ssl$ openssl genrsa -out privkey.pem 1024 > Generating RSA private key, 1024 bit long modulus > ..........................................................++++++ > .++++++ > e is 65537 (0x10001) > sven@netbook:~/ssl$ openssl req -new -key privkey.pem -out certreq.csr > You are about to be asked to enter information that will be incorporated > into your certificate request. > What you are about to enter is what is called a Distinguished Name or a DN. > There are quite a few fields but you can leave some blank > For some fields there will be a default value, > If you enter '.', the field will be left blank. > ----- > Country Name (2 letter code) [AU]:BE > State or Province Name (full name) [Some-State]: > Locality Name (eg, city) []:Hasselt > Organization Name (eg, company) [Internet Widgits Pty Ltd]:STfx.eu > Organizational Unit Name (eg, section) []: > Common Name (e.g. server FQDN or YOUR name) []:Sven Van Caekenberghe > Email Address []:sven@stfx.eu > > Please enter the following 'extra' attributes > to be sent with your certificate request > A challenge password []: > An optional company name []: > sven@netbook:~/ssl$ ls > certreq.csr privkey.pem > sven@netbook:~/ssl$ openssl x509 -req -days 3650 -in certreq.csr -signkey > privkey.pem -out newcert.pem > Signature ok > subject=/C=BE/ST=Some-State/L=Hasselt/O=STfx.eu/CN=Sven Van > Caekenberghe/emailAddress=sven(a)stfx.eu > Getting Private key > sven@netbook:~/ssl$ ( openssl x509 -in newcert.pem; cat privkey.pem ) > > server.pem > > > > (ZnSecureServer on: 1443) > certificate: '/home/sven/ssl/server.pem'; > logToTranscript; > start; > yourself. > > === > > HTH, > > Let me know when you get it working. > > Sven > > > On 27 Nov 2014, at 09:23, Max Leske <maxleske(a)gmail.com> wrote: > > > > > http://stackoverflow.com/questions/27162749/znsecureserver-on-pharo3-0-on-u… > > >

Nov. 27, 2014

[Pharo4] saveAs now uses save file dialog

by Marcus Denker

Hi, One of the things that is very confusing for people using Pharo is that there is no way to save the image to another directory (or even know in which directory is is saved). #386 now uses the standard saveAs dialog. (thanks to Nicolai Hess) Further improvement: => it should be improved to have a name pre-set (like before, with the increasing number) => Of course the save as dialog could be improved, but it should be usable as it is. Marcus

Nov. 27, 2014

Re: [Pharo-dev] [SO] SSL exception with ZnSecureServer

by Sven Van Caekenberghe

I just sent the OP this in reply to a private message ;-) Hi Monty, It should work on Linux. This is how I once did it (making the certificate), more than a year ago (I know that others have managed to do this too): ==== sven@netbook:~/ssl$ openssl genrsa -out privkey.pem 1024 Generating RSA private key, 1024 bit long modulus ..........................................................++++++ .++++++ e is 65537 (0x10001) sven@netbook:~/ssl$ openssl req -new -key privkey.pem -out certreq.csr You are about to be asked to enter information that will be incorporated into your certificate request. What you are about to enter is what is called a Distinguished Name or a DN. There are quite a few fields but you can leave some blank For some fields there will be a default value, If you enter '.', the field will be left blank. ----- Country Name (2 letter code) [AU]:BE State or Province Name (full name) [Some-State]: Locality Name (eg, city) []:Hasselt Organization Name (eg, company) [Internet Widgits Pty Ltd]:STfx.eu Organizational Unit Name (eg, section) []: Common Name (e.g. server FQDN or YOUR name) []:Sven Van Caekenberghe Email Address []:sven@stfx.eu Please enter the following 'extra' attributes to be sent with your certificate request A challenge password []: An optional company name []: sven@netbook:~/ssl$ ls certreq.csr privkey.pem sven@netbook:~/ssl$ openssl x509 -req -days 3650 -in certreq.csr -signkey privkey.pem -out newcert.pem Signature ok subject=/C=BE/ST=Some-State/L=Hasselt/O=STfx.eu/CN=Sven Van Caekenberghe/emailAddress=sven(a)stfx.eu Getting Private key sven@netbook:~/ssl$ ( openssl x509 -in newcert.pem; cat privkey.pem ) > server.pem (ZnSecureServer on: 1443) certificate: '/home/sven/ssl/server.pem'; logToTranscript; start; yourself. === HTH, Let me know when you get it working. Sven > On 27 Nov 2014, at 09:23, Max Leske <maxleske(a)gmail.com> wrote: > > http://stackoverflow.com/questions/27162749/znsecureserver-on-pharo3-0-on-u…

Nov. 27, 2014

[pharo-project/pharo-core]

by GitHub

Branch: refs/tags/40386 Home: https://github.com/pharo-project/pharo-core

Nov. 27, 2014

[pharo-project/pharo-core] 0dfcfd: 40386

by GitHub

Branch: refs/heads/4.0 Home: https://github.com/pharo-project/pharo-core Commit: 0dfcfd5f7b3aa8037c9356204dd8a9989aec7494 https://github.com/pharo-project/pharo-core/commit/0dfcfd5f7b3aa8037c935620… Author: Jenkins Build Server <board(a)pharo-project.org> Date: 2014-11-27 (Thu, 27 Nov 2014) Changed paths: M Morphic-Core.package/WorldState.class/class/world menu items/saveAs.st M NautilusCommon.package/GoBackStringMorph.class/instance/stepping and presenter/stepBackward.st M NautilusCommon.package/GoBackStringMorph.class/instance/stepping and presenter/stepFrontward.st M NautilusCommon.package/KonamiCodePlugin.class/instance/announcement/keyPressed_.st M NautilusCommon.package/NautilusHistoryEntry.class/instance/protocol/asHistoryString.st M NautilusCommon.package/extension/CompiledMethod/instance/correspondingMethods.st M NautilusCommon.package/extension/CompiledMethod/instance/correspondingTestMethod.st M NautilusCommon.package/extension/RGMethodDefinition/instance/correspondingMethods.st M NautilusCommon.package/extension/RGMethodDefinition/instance/correspondingTestMethod.st A ScriptLoader40.package/ScriptLoader.class/instance/pharo - scripts/script386.st A ScriptLoader40.package/ScriptLoader.class/instance/pharo - updates/update40386.st M ScriptLoader40.package/ScriptLoader.class/instance/public/commentForCurrentUpdate.st Log Message: ----------- 40386 14525 tiny code critic clean NautilusCommon https://pharo.fogbugz.com/f/cases/14525 6320 We need a "Save As" Dialog https://pharo.fogbugz.com/f/cases/6320 http://files.pharo.org/image/40/40386.zip

Nov. 27, 2014

[SO] SSL exception with ZnSecureServer

by Max Leske

http://stackoverflow.com/questions/27162749/znsecureserver-on-pharo3-0-on-u…

Nov. 27, 2014

Re: [Pharo-dev] Stream instead of string concatenation

by Max Leske

> On 26.11.2014, at 17:32, Ben Coman <btc(a)openInWorld.com> wrote: > > Yuriy Tymchuk wrote: >> Hi everyone! >> There is a Lint rule that suggests to use stream instead of strings concatenation. What is the most common way, to create a string this way, because the only thing I can come up with is: >> String streamContents: [ :stream | >> stream >> nextPutAll: 'Hello'; >> nextPut: $ ; >> nextPutAll: 'Worldâ] >> But Iâm not sure if it is the preferred solution. >> Cheers >> Uko > > This is typical advise, but previous discussion found it to be not necessarily true. > > https://www.mail-archive.com/pharo-dev@lists.pharo.org/msg08162.html > Very good advice, thanks Ben! > Perhaps the rule should be ammended/deleted. Maybe a metric can be derived from Svenâs observations, e.g. âdonât apply if the strings are constantsâ etc. I donât think the rule should be deleted because in the general case itâs important to understand that streams can be more efficient. > cheers -ben > >

Nov. 27, 2014

Re: [Pharo-dev] Float class comment

by Marcus Denker

I added an issue tracker entry 14536 Float class comment https://pharo.fogbugz.com/f/cases/14536 > On 25 Nov 2014, at 18:42, Eliot Miranda <eliot.miranda(a)gmail.com> wrote: > > Hi All, > > who wrote the Float class comment? Two things, > > - first the comment mentions "I" and thanks several people, but there is no comment stamp to reveal the author. It would be lovely if the author could "sign" this comment > > - second, there seems to be a minor error (but I'm no expert), the comment states > > "It may help you to know that the basic format is... > sign 1 bit > exponent 11 bits with bias of 1023 (16r3FF) to produce an exponent > in the range -1023 .. +1024 > - 16r000: > significand = 0: Float zero > significand ~= 0: Denormalized number (exp = -1024, no hidden '1' bit) > - 16r7FF: > significand = 0: Infinity > significand ~= 0: Not A Number (NaN) representation > mantissa 53 bits, but only 52 are stored (20 in the first word, 32 in the second). This is because a normalized mantissa, by definition, has a 1 to the right of its floating point, and IEEE-754 omits this redundant bit to gain an extra bit of precision instead. People talk about the mantissa without its leading one as the FRACTION, and with its leading 1 as the SIGNFICAND." > > But if the significand has a leading zero then surely the section in the middle should read > > sign 1 bit > exponent 11 bits with bias of 1023 (16r3FF) to produce an exponent > in the range -1023 .. +1024 > - 16r000: > mantissa = 0: Float zero > mantissa ~= 0: Denormalized number (exp = -1024, no hidden '1' bit) > - 16r7FF: > mantissa = 0: Infinity > mantissa ~= 0: Not A Number (NaN) representation > > Right? > -- > best, > Eliot

Nov. 27, 2014

[pharo-project/pharo-core]

by GitHub

Branch: refs/tags/40385 Home: https://github.com/pharo-project/pharo-core

Nov. 27, 2014