Followup to this question. Groovy.codehaus.org just refers to it as a token. Are there any informal monikers floating around like 'splat' and 'bang'?
It is informally known as "the arrow". I cite this post from 2008. Though I can't claim it is a standard idiom, I've never heard it called anything else (in conversation).
In the antlr parser script, it's called the 'closable block operator'
I don't know of a snappier name than 'arrow'
I've heard it called "Rocket" before.
Also a "Fat Rocket"/"Hash Rocket" would be '=>'
But this more applies to Ruby lingo.
Related
My program, PKGDAYMONR has the control option:
ctl-opt Main( CheckDailyPackages )
The CheckDailyPackages procedure has the following PI:
dcl-pi *n ExtPgm( 'PGMNAME' );
As you can see the ExtPgm parameter is not the name of the program. In fact, it’s what came over in the template source and I forgot to change it. Despite the wrong name in ExtPgm, the program runs without a problem.
If I remove that parameter and leave the keyword as just ExtPgm, I get the following message:
RNF3573: A parameter is required for the EXTPGM keyword when the
procedure name is longer than 10.
If I drop ExtPgm from the Procedure Interface altogether, it also complains:
RNF3834: EXTPGM must be specified on the prototype for the MAIN()
procedure.
So why is it that I have to specify a parameter if it doesn't matter what value I enter?
O/S level: IBM i 7.2
Probably worth pursuing as a defect with the service provider; presumably for most, that would be IBM rather than a third-party, as they would have to contact IBM anyhow, given the perceived issue is clearly with their compiler. Beyond that, as my "Answer", I offer some thoughts:
IMO, and in apparent agreement with the OP, naming the ExtPgm seems pointless in the given scenario. I think the compiler is confused while trying to enforce some requirements in validations of the implicitly generated Prototype for the linear-main for which only a Procedure Interface is supplied; i.e. enforcing requirements that are appropriate for an explicit Prototype, but requirements that could be overlooked [thus are no longer requirements] in the given scenario.? I am suggesting that while the RNF3573 would seem appropriate for diagnosing EXTPGM specifications of an explicit Prototype, IMO that same effect is inappropriate [i.e. the validation should not be performed] for an implicit prototype that was generated by the compiler.
FWiW: Was the fixed-format equivalent of that free-form code tested, to see if the same or a different error was the effect? The following source code currently includes the EXTPGM specification with 'PGMNAME' as the argument [i.e. supplying any bogus value of 10-byte naming to supplicate the compiler, just as is being done in the scenario of the OP, solely to effect a successful compile], but could be compiled with the other variations with changes to the source, mimicking what was done with free-form variations, to test if the same\consistent validations and errors are the effect:
- just EXTPGM keyword coded (w/out argument); is RNF3573 the effect?
- the EXTPGM keyword could be omitted; is RNF3834 the effect?
- the D-spec removed entirely (if there are no parameters defined); ¿that was not one of the variations noted in the OP as being tried, so... the effect?
H MAIN(CheckDailyPackages)
*--------------------------------------------------
* Program name: CheckDailyPackages (PGMNAME)
*--------------------------------------------------
P CheckDailyPackages...
P B
D PI EXTPGM('PGMNAME')
/free
// Work is done here
/end-free
P CheckDailyPackages...
P E
I got a response from IBM and essentially Biswa was on to something, it simply wasn't clear (in my opinion) about the answer.
Essentially the EXTPGM is required on long Main procedure names in order to support recursive program calls.
This is the response I received from IBM explaining the reason for the scenario:
The incorrect EXTPGM would only matter if there was a call to the main
procedure (the program) within the module.
When the compiler processes the procedure interface, it doesn't know
whether there might be a call that appears later in the module.
EXTPGM keyword is used to define the external name of the program which you want to prototype. If you mention the EXTPGM then the program will be called dynamically.
Let us take an example in order to explain your query.
PGMA
D cmdExc PR ExtPgm('QSYS/QCMDEXC')
D 200A const
D 15P05 const
c callp cmdExc('CLRPFM LIB1/PF1':200)
C Eval *INLR = *ON
In the above example CmdExc used for the dynamic call to QSYS/QCMDEXC.
When we use the same program name as the EXTPGM parameter it acts as an entry point to the program when called from other programs or procedure.
But in any case when we mention any name as the sample parameter the EXTPGM will not give any error in compilation, but it gives the error during run time as it tries to resolve the name during run time.
I am attempting to learn Smalltalk through the tutorials included with Dolphin Smalltalk X6.
My question deals with the evaluation of expressions with multiple messages.
My understanding is that simple messages are evaluated first, then binary messages, and finally keyword messages (with the exception of code in parenthesis). However, I am having trouble applying this understanding to the second line in the following example (found in the Dolphin Smalltalk tutorial).
playground := Playground new.
teresa := playground add: Triangle new. "Misunderstood code"
teresa class. "Evaluates to 'Triangle'"
If my understanding were correct, the 2nd line would be evaluated thusly:
1. Simple message 'new' sent to Triangle, triangle object as response
2. Binary message ':=' with parameter 'playground' sent to 'teresa'.
3. Keyword message 'add:' with parameter 'triangle object' sent to 'teresa'.
4. teresa class. "evaluates to 'Playground'".
My misunderstanding is in how 'teresa' comes to refer to the anonymous Triangle object and not the Playground object referred to by 'playground'.
I have looked up a second explanation of Smalltalk evaluation for mentions of := or add: being special cases with no success, and the only other explanation I can think of is a fundamental misunderstanding.
Any help straightening me out?
The Assignment operator (:=) isn't a message. (It's not sent to an object, instead it indicates that a variable should be set to a value). Its precedence is last overall.
So what happens is:
Simple message 'new' send to Triangle, triangle object as response
keyword message add: sent to playground, and there's a convention that add: messages answer the object added, which this one seems to follow, so the newly created triangle is returned.
The variable teresa is set to the new triangle
teresa class. "evaluates to Triangle".
While := looks like a binary message because it uses infix characters... it is not. It's a part of the language syntax in the same way that parens and periods are (for example).
Think of := as the assignment operator (sometimes spoken as "gets"). It is NOT a message of any precedence. It is evaluated AFTER any message sends. It's lvalue MUST be a direct variable reference (not the results of a message send).
Consider the following sample codes:
1.Sample
var IsAdminUser = (User.Privileges == AdminPrivileges)
? 'yes'
: 'no';
console.log(IsAdminUser);
2.Sample
var IsAdminUser = (User.Privileges == AdminPrivileges)?'yes': 'no';
console.log(IsAdminUser);
The 2nd sample I am very comfortable with & I code in that style, but it was told that its wrong way of doing without any supportive reasons.
Why is it recommended not to use a single line ternary operator in Node.js?
Can anyone put some light on the reason why it is so?
Advance Thanks for great help.
With all coding standards, they are generally for readability and maintainability. My guess is the author finds it more readable on separate lines. The compiler / interpreter for your language will handle it all the same. As long as you / your project have a set standard and stick to it, you'll be fine. I recommend that the standards be worked on or at least reviewed by everyone on the project before casting them in stone. I think that if you're breaking it up on separate lines like that, you may as well define an if/else conditional block and use that.
Be wary of coding standards rules that do not have a justification.
Personally, I do not like the ternary operator as it feels unnatural to me and I always have to read the line a few times to understand what it's doing. I find separate if/else blocks easier for me to read. Personal preference of course.
It is in fact wrong to put the ? on a new line; even though it doesn’t hurt in practice.
The reason is a JS feature called “Automatic Semicolon Insertion”. When a var statement ends with a newline (without a trailing comma, which would indicate that more declarations are to follow), your JS interpreter should automatically insert a semicolon.
This semicolon would have the effect that IsAdminUser is assigned a boolean value (namely the result of User.Privileges == AdminPrivileges). After that, a new (invalid) expression would start with the question mark of what you think is a ternary operator.
As mentioned, most JS interpreters are smart enough to recognize that you have a newline where you shouldn’t have one, and implicitely fix your ternary operator. And, when minifying your script, the newline is removed anyway.
So, no problem in practice, but you’re relying on an implicit fix of common JS engines. It’s better to write the ternary operator like this:
var foo = bar ? "yes" : "no";
Or, for larger expressions:
var foo = bar ?
"The operation was successful" : "The operation has failed.";
Or even:
var foo = bar ?
"Congratulations, the operation was a total success!" :
"Oh, no! The operation has horribly failed!";
I completely disagree with the person who made this recommendation. The ternary operator is a standard feature of all 'C' style languages (C,C++,Java,C#,Javascript etc.), and most developers who code in these languages are completely comfortable with the single line version.
The first version just looks weird to me. If I was maintaining code and saw this, I would correct it back to a single line.
If you want verbose, use if-else. If you want neat and compact use a ternary.
My guess is the person who made this recommendation simply wasn't very familiar with the operator, so found it confusing.
Because it's easier on the eye and easier to read. It's much easier to see what your first snippet is doing at a glance - I don't even have to read to the end of a line. I can simply look at one spot and immediately know what values IsAdminUser will have for what conditions. Much the same reason as why you wouldn't write an entire if/else block on one line.
Remember that these are style conventions and are not necessarily backed up by objective (or technical) reasoning.
The reason for having ? and : on separate lines is so that it's easier to figure out what changed if your source control has a line-by-line comparison.
If you've just changed the stuff between the ? and : and everything is on a single line, the entire line can be marked as changed (based on your comparison tool).
This is PascalCase: SomeSymbol
This is camelCase: someSymbol
This is snake_case: some_symbol
So my questions is whether there is a widely accepted name for this: some-symbol? It's commonly used in url's.
There isn't really a standard name for this case convention, and there is disagreement over what it should be called.
That said, as of 2019, there is a strong case to be made that kebab-case is winning:
https://trends.google.com/trends/explore?date=all&q=kebab-case,spinal-case,lisp-case,dash-case,caterpillar-case
spinal-case is a distant second, and no other terms have any traction at all.
Additionally, kebab-case has entered the lexicon of several javascript code libraries, e.g.:
https://lodash.com/docs/#kebabCase
https://www.npmjs.com/package/kebab-case
https://v2.vuejs.org/v2/guide/components-props.html#Prop-Casing-camelCase-vs-kebab-case
However, there are still other terms that people use. Lisp has used this convention for decades as described in this Wikipedia entry, so some people have described it as lisp-case. Some other forms I've seen include caterpillar-case, dash-case, and hyphen-case, but none of these is standard.
So the answer to your question is: No, there isn't a single widely-accepted name for this case convention analogous to snake_case or camelCase, which are widely-accepted.
It's referred to as kebab-case. See lodash docs.
It's also sometimes known as caterpillar-case
This is the most famous case and It has many names
kebab-case: It's the name most adopted by official software
caterpillar-case
dash-case
hyphen-case or hyphenated-case
lisp-case
spinal-case
css-case
slug-case
friendly-url-case
As the character (-) is referred to as "hyphen" or "dash", it seems more natural to name this "dash-case", or "hyphen-case" (less frequently used).
As mentioned in Wikipedia, "kebab-case" is also used. Apparently (see answer) this is because the character would look like a skewer... It needs some imagination though.
Used in lodash lib for example.
Recently, "dash-case" was used by
Angular (https://angular.io/guide/glossary#case-types)
NPM modules
https://www.npmjs.com/package/case-dash (removed ?)
https://www.npmjs.com/package/dasherize
Adding the correct link here Kebab Case
which is All lowercase with - separating words.
I've always called it, and heard it be called, 'dashcase.'
There is no standardized name.
Libraries like jquery and lodash refer it as kebab-case. So does Vuejs javascript framework. However, I am not sure whether it's safe to declare that it's referred as kebab-case in javascript world.
I've always known it as kebab-case.
On a funny note, I've heard people call it a SCREAM-KEBAB when all the letters are capitalized.
Kebab Case Warning
I've always liked kebab-case as it seems the most readable when you need whitespace. However, some programs interpret the dash as a minus sign, and it can cause problems as what you think is a name turns into a subtraction operation.
first-second // first minus second?
ten-2 // ten minus two?
Also, some frameworks parse dashes in kebab cased property. For example, GitHub Pages uses Jekyll, and Jekyll parses any dashes it finds in an md file. For example, a file named 2020-1-2-homepage.md on GitHub Pages gets put into a folder structured as \2020\1\2\homepage.html when the site is compiled.
Snake_case vs kebab-case
A safer alternative to kebab-case is snake_case, or SCREAMING_SNAKE_CASE, as underscores cause less confusion when compared to a minus sign.
I'd simply say that it was hyphenated.
Worth to mention from abolish:
https://github.com/tpope/vim-abolish/blob/master/doc/abolish.txt#L152
dash-case or kebab-case
In Salesforce, It is referred as kebab-case. See below
https://developer.salesforce.com/docs/component-library/documentation/lwc/lwc.js_props_names
Here is a more recent discombobulation. Documentation everywhere in angular JS and Pluralsight courses and books on angular, all refer to kebab-case as snake-case, not differentiating between the two.
Its too bad caterpillar-case did not stick because snake_case and caterpillar-case are easily remembered and actually look like what they represent (if you have a good imagination).
My ECMAScript proposal for String.prototype.toKebabCase.
String.prototype.toKebabCase = function () {
return this.valueOf().replace(/-/g, ' ').split('')
.reduce((str, char) => char.toUpperCase() === char ?
`${str} ${char}` :
`${str}${char}`, ''
).replace(/ * /g, ' ').trim().replace(/ /g, '-').toLowerCase();
}
This casing can also be called a "slug", and the process of turning a phrase into it "slugify".
https://hexdocs.pm/slugify/Slug.html
I want to read from a file in Visual Haskell Studio, token after token, by loading each time the next token in a variable.
For example: getNextToken.
Thanks!! :)
You can use Alex, which is a lexer (which split a string into a list of tokens). Then you can do whatever you want with the token list. If you really want to "load" them and put them in a variable, in a procedural way , I'm not sure Haskell is the right language to do it.
Well, the right answer is somewhat complicated:
Use a parser combinator library like Parsec that will let you fully define the meaning of the word 'token', which varies from context to context.