April 2020 - Pharo-users - lists.pharo.org

Re: [Pharo-users] mentor question 2.
by Richard O'Keefe April 29, 2020

April 29, 2020

String>> isValidBinary ^self allSatisfy: [:each | each = $0 or: [each = $1]] binaryToDecimal "The caller should ensure that self isValidBinary before calling this." ^self inject: 0 into: [:acc :each | acc*2 + (each codePoint - $0 codePoint)] On Mon, 27 Apr 2020 at 06:05, Roelof Wobben via Pharo-users <pharo-users(a)lists.pharo.org> wrote: > > Hello, > > I have to make some code that convert a binary to a decimal and im not > allowed to use the convert methods that Pharo has. > > So I have written this : > > > decimalFromBinary: aString > | result isValid | > isValid = self isValidBinary: aString. > isValid > ifTrue: [ result := 0. > aString reverse > withIndexDo: > [ :digit :index | result := result + (digit > digitValue * (2 raisedTo: index - 1)) ]. > ^ result ] > ifFalse: [ ^ nil ] > > isValidBinary: aString > ^ aString allSatisfy: [ :c | c = 0 or: [ c = 1 ] ] > > > but on the first method I see a message that the temp variables are read > before written. > and the second one I see a message that I use a or instead of searching > literals. > > Where did I think wrong here ? > > Roelof > >

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mentor question 3 is there a formula for this
by Roelof Wobben April 28, 2020

April 28, 2020

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Re: [Pharo-users] can I divide a string into part of exactly n length
by Richard O'Keefe April 27, 2020

April 27, 2020

|s1 s2| s1 := 'abcdefghijk'. s2 := String streamContents: [:s | s1 keysAndValuesDo: [:index :each | (index \\ 3 = 1 and: [1 < index]) ifTrue: [s space]. s nextPut: each]]. is perhaps a little simpler. I generally prefer to have Smalltalk do the counting for me. On Tue, 28 Apr 2020 at 07:25, Todd Blanchard via Pharo-users <pharo-users(a)lists.pharo.org> wrote: > > This works > > | s1 s2 | > s1 := 'abcdefghijk'. > s2 := String streamContents: [:s || in len | > in := ReadStream on: s1. > len := 0. > [in atEnd] whileFalse: [ > s nextPut: in next. > len := len + 1. > (in atEnd not and: [ (len \\ 3) = 0]) ifTrue: [ s space ] ] ] > > On Apr 27, 2020, at 10:07 AM, Roelof Wobben via Pharo-users <pharo-users(a)lists.pharo.org> wrote: > > > From: Roelof Wobben <r.wobben(a)home.nl> > Subject: Re: [Pharo-users] can I divide a string into part of exactly n length > Date: April 27, 2020 at 10:07:41 AM PDT > To: Richard Sargent <richard.sargent(a)gemtalksystems.com>, Any question about pharo is welcome <pharo-users(a)lists.pharo.org> > > > Op 27-4-2020 om 19:05 schreef Richard Sargent: > > On Mon, Apr 27, 2020 at 9:27 AM Roelof Wobben via Pharo-users <pharo-users(a)lists.pharo.org> wrote: >> >> Hello, >> >> I wonder if it is possible in Pharo to divide a string in lets say part >> of 3. >> so this : 'abcdefgh' >> >> would be 'abc def gh` > > > Do you really want a single string with spaces inserted or do you want a collection of substrings, each three characters (or less, for the last one)? > > > I need a single string with spaces inserted. > So maybe I have formulate my question wrong. Very difficult if English is not your mother language and you were bad at school in languages a very very long ago. > > Roelof > > > >

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Re: [Pharo-users] how can I test this
by Richard O'Keefe April 27, 2020

April 27, 2020

You wrote "I want to test if the response back to the sending node is the same string as the sending node is but then all uppercased." What is wrong with received = sent asUppercase ? If for some reason you don't like that, then received class = sent class and: [ received size = sent size and: [ received with: sent allSatisfy: [:r :s | r = s asUppercase]]] might do the job, but for two things. (1) SequenceableCollection>> with: another allSatisfy: testBlock "Extension of Collection>>allSatisfy: to test whether corresponding elements of two sequences already known to be the same length all satisfy the given test." self with: another do: [:x :y | (testBlock value: x value: y) ifFalse: [^false]]. ^true is not in Pharo 7. (2) Case conversion in Unicode is *not* a code-point by code-point mapping; it can change the length of a string. received = sent asUppercase is not just the simplest way, it's the safest. On Tue, 28 Apr 2020 at 05:04, Roelof Wobben via Pharo-users <pharo-users(a)lists.pharo.org> wrote: > > Op 27-4-2020 om 18:28 schreef Richard Sargent: > > On Mon, Apr 27, 2020 at 1:56 AM Roelof Wobben via Pharo-users <pharo-users(a)lists.pharo.org> wrote: >> >> Hello, >> >> I have to test the server which should return the string but then in >> uppercase. >> >> So far I have this : >> https://github.com/RoelofWobben/Network-simulator/blob/master/src/NetworkSi… >> >> but I fail to see how I can test that the package sending back is a >> uppercase string. > > > I think you need to rephrase this question. Either the String class hierarchy has a method named something like #isUppercase or Character does. If only Character has it, you would need to iterate over the received string testing each individual character. > > Or is your question more about getting the response back to the sending node? > > > yep, I want to test if the response back to the sending node is the same string as the sending node is but then all uppercased. > > Roelof >

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Re: [Pharo-users] how can I test this
by Roelof Wobben April 27, 2020

April 27, 2020

Op 27-4-2020 om 19:50 schreef Roelof Wobben via Pharo-users: This seems to be working testKaNetWorkServer Â Â Â | srcNode destNode link packet link2 packet2 recievedPackage | Â Â Â srcNode := KANetworkNode withAddress: #src. Â Â Â destNode := KANetworkServer withAddress: #dest. Â Â Â link := (KANetworkLink from: srcNode to: destNode) Â Â Â Â Â Â attach; Â Â Â Â Â Â yourself. Â Â Â link2 := (KANetworkLink from: destNode to: srcNode) Â Â Â Â Â Â attach; Â Â Â Â Â Â yourself. Â Â Â packet := KANetworkPacket from: #src to: #dest payload: 'test'. Â Â Â srcNode send: packet via: link. Â Â Â destNode consume: packet. Â Â Â packet2 := link2 packetsToTransmit first. Â Â Â srcNode receive: packet2 from: destNode. Â Â Â recievedPackage := srcNode arrivedPackets first. Â Â Â self assert: recievedPackage payload equals: 'TEST' I hope it is a good one.

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Re: [Pharo-users] can I divide a string into part of exactly n length
by Todd Blanchard April 27, 2020

April 27, 2020

This works | s1 s2 | s1 := 'abcdefghijk'. s2 := String streamContents: [:s || in len | in := ReadStream on: s1. len := 0. [in atEnd] whileFalse: [ s nextPut: in next. len := len + 1. (in atEnd not and: [ (len \\ 3) = 0]) ifTrue: [ s space ] ] ] > On Apr 27, 2020, at 10:07 AM, Roelof Wobben via Pharo-users <pharo-users(a)lists.pharo.org> wrote: > > > From: Roelof Wobben <r.wobben(a)home.nl> > Subject: Re: [Pharo-users] can I divide a string into part of exactly n length > Date: April 27, 2020 at 10:07:41 AM PDT > To: Richard Sargent <richard.sargent(a)gemtalksystems.com>, Any question about pharo is welcome <pharo-users(a)lists.pharo.org> > > > Op 27-4-2020 om 19:05 schreef Richard Sargent: >> On Mon, Apr 27, 2020 at 9:27 AM Roelof Wobben via Pharo-users <pharo-users(a)lists.pharo.org <mailto:pharo-users@lists.pharo.org>> wrote: >> Hello, >> >> I wonder if it is possible in Pharo to divide a string in lets say part >> of 3. >> so this : 'abcdefgh' >> >> would be 'abc def gh` >> >> Do you really want a single string with spaces inserted or do you want a collection of substrings, each three characters (or less, for the last one)? >> > > I need a single string with spaces inserted. > So maybe I have formulate my question wrong. Very difficult if English is not your mother language and you were bad at school in languages a very very long ago. > > Roelof > > >

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Re: [Pharo-users] how can I test this
by Richard Sargent April 27, 2020

April 27, 2020

On Mon, Apr 27, 2020 at 1:56 AM Roelof Wobben via Pharo-users < pharo-users(a)lists.pharo.org> wrote: > Hello, > > I have to test the server which should return the string but then in > uppercase. > > So far I have this : > > https://github.com/RoelofWobben/Network-simulator/blob/master/src/NetworkSi… > > but I fail to see how I can test that the package sending back is a > uppercase string. > I think you need to rephrase this question. Either the String class hierarchy has a method named something like #isUppercase or Character does. If only Character has it, you would need to iterate over the received string testing each individual character. Or is your question more about getting the response back to the sending node? > Regards, > > Roelof > > > > >

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Re: [Pharo-users] can I divide a string into part of exactly n length
by Richard Sargent April 27, 2020

April 27, 2020

On Mon, Apr 27, 2020 at 9:27 AM Roelof Wobben via Pharo-users < pharo-users(a)lists.pharo.org> wrote: > Hello, > > I wonder if it is possible in Pharo to divide a string in lets say part > of 3. > so this : 'abcdefgh' > > would be 'abc def gh` > Do you really want a single string with spaces inserted or do you want a collection of substrings, each three characters (or less, for the last one)? > Regards, > > Roelof > > >

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Re: [Pharo-users] mentor question 2.
by Richard Sargent April 27, 2020

April 27, 2020

On Sun, Apr 26, 2020 at 10:11 AM Roelof Wobben via Pharo-users < pharo-users(a)lists.pharo.org> wrote: > Hello, > > I have to make some code that convert a binary to a decimal and im not > allowed to use the convert methods that Pharo has. > > So I have written this : > > > decimalFromBinary: aString > | result isValid | > isValid = self isValidBinary: aString. > isValid > ifTrue: [ result := 0. > aString reverse > withIndexDo: > [ :digit :index | result := result + (digit > digitValue * (2 raisedTo: index - 1)) ]. > ^ result ] > ifFalse: [ ^ nil ] > > isValidBinary: aString > ^ aString allSatisfy: [ :c | c = 0 or: [ c = 1 ] ] > Others have answered your question, so I'll limit my response to other aspects of this exercise. Answering nil is a bad practice, in general. There will be occasions where it is correct, if non-existence really is part of the model. Answering nil may have been a requirement of the exercise and if that's the case, you have no choice. By answering nil, you force every sender to check for nil rather than being able to rely on receiving an Integer result. Even with method selectors that tell the reader a nil can be the result, too many people will fail to check the result before using it. In general, I prefer to have the validation throw an exception. e.g. validateBinaryString: aString (aString allSatisfy: [:each | '01' includes: each]) ifFalse: [self error: aString printString, ' is not a valid representation of a binary number']. The method simply returns self if it succeeds or throws an exception is the string is invalid. And likewise, the conversion method itself only answers the integer corresponding to a valid binary string and does not answer (anything) for an invlaid one. There is another pattern that could be used, but this particular problem seems (to me) best suited to an exception. A common pattern in Smalltalk, one of its greatest innovations, is the #ifAbsent: keyword and others like it. When you send #at:ifAbsent:, *you* tell the receiver to give you what you ask for *and* you tell it what *you* want to do if it cannot. There are infinitely many possible keywords like #ifAbsent:, as you can make up any one that suits your needs. If you look at the implementation of #at: or #detect:, you will see that they are implemented using #at:ifAbsent: and #detect:ifNone: and that the block provided for the second argument is one which throws an error. Given all that, perhaps the "best" implementation of your solution would be to have "decimalFromBinary: aString" implemented in terms of a "decimalFromBinary: aString ifUnable: aBlock". > > but on the first method I see a message that the temp variables are read > before written. > and the second one I see a message that I use a or instead of searching > literals. > > Where did I think wrong here ? > > Roelof > > >

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Non-blocking IO
by dturczanski April 27, 2020

April 27, 2020

Hi guys, I'm wondering whether Pharo support any form of non-blocking IO. You can find such IO support in Node.js or Java NIO packages and on Linux they use select/poll async IO system calls. An example scenario is to be able to schedule 10 concurrent HTTP calls taking 1-5s and wait for them to finish. Naturally, if you perform the calls sequentially you'll wait for much longer than if you fire the calls concurrently. Is it possible in Pharo? I've only spent a few hours reading about the platform but I'm still not sure whether the built-in process/threading supports such scenario. -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

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