I found two lines in my code.
test = new qx.ui.form.RadioGroup;
I am wondering, if the missing () might cause issues or should maybe raise a warning in the generator or the lint job.
qx.ui.form.RadioGroup;
I think it might be worth reporting it as a "statement without effect" in lint.
mck89's comment is the answer (I wonder why so many people put valid answers in comments...):
You don't need the parens, and new qx.ui.form.RadioGroup is a syntactically correct expression, equivalent to adding a pair of empty parens. (There are some checkers that will warn about this, like I believe JsLint, but qooxdoo doesn't ... :).
In your particular case, the code will also run successfully in the browser, as RadioGroup permits empty constructor args; you can use .add() later to add items to the group.
Related
I have an argument with my compilation course lecturer:
In the test that was part of this course, some of the questions referred the identification and classification code segments written in C.
Each of these questions must indicate at what stage the error will expose:
a.Lexical analysis
b. Synthetic analysis
c. Semantic analysis
d. Running time (under certain conditions)
e. This is not an error.
One of the questions in this style was as follows:
Switch command that does not have the default component. For example:
switch (key){
case 1: .........
case 2: .........
case 3:..........
}
Now, in the official test solution, in the above case only option e was correct.
However, I argue that Option d cannot necessarily be rejected outright, and that it is also true.
As an argument, I showed (after the test) the following two examples to my lecturer:
1)
(from : https://cwe.mitre.org/data/definitions/478.html)
2)
(from : Should switch statements always contain a default clause?)
However, he is not yet convinced that the runtime error option is considered in this case. He said that because of the questions mentioned above, it is only for commands or snippets that are shown directly in the questions and because the code does not have the intent of the code, so in this case they are actually asking if this structure is by itself invalid, so you are denied a runtime error here (I personally do not notice any contradictory here ...).
I would be happy if you could share your views on this issue.
Your lecturer is correct.
Omitting the default case in a switch is perfectly valid code and will not directly lead to any kind of problem. It may well be exactly what the programmer intended, and do the correct thing.
Of course, it is always possible to add some code that would cause problems, but that is a problem with this added code, not with the switch per se. Code style rules like "always add a default case" may guard against certain types of programming mistakes, but not following them does not automatically cause these mistakes - it "just" requires more caution.
From a code style perspective, it is usually better to be explicit about intentionally ignoring certain cases, or to add some default handler for guarding against unexpected values, but that does not mean that omitting such a handler is always incorrect by itself.
(Note that the currently second most upvoted answer in the question you linked to yourself argues for omitting default cases that are not doing anything useful, in order to reduce clutter - I don't fully agree with that, but it is a matter of style)
I work in safety critical application development. Recently as a code reviewer I complained against coding style shown below, but couldn't make a strong case against it. So what would be a good argument against such Variable redundancy/duplication, I am looking for cases where this might lead to problems or test cases which might fail, rather than just coding style.
//global data
// global data
int Block1Var;
int Block2Var;
...
//Block1
{
...
Block1Var = someCondition; // someCondition is an logical expression
...
}
//Block2
{
...
Block2Var = Block1Var; // Block2Var is an unconditional copy of Block1Var
...
}
I think a little more context would be helpful perhaps.
You could argue that the value of Block1Var is not guaranteed to stay the
same across concurrent access/modification. This is only valid if Block1Var
ever changes (ie is not only read). I don't know if you are concerned with
multi-threaded applications or not.
Readability is an important issue as well. Future code maintainers
don't want to have to trace around a bunch of trivial assignments.
Depends on what's done with those variables later, but one argument is that it's not future-proof. If, in the future, you change the code such that it changes the value of Block1Var, but Block2Var is used instead (without the additional change) later on, then this will result in erroneous behavior.
If the shown function context reaches a certain length (I'm assuming a lot of detail has been discarded to create the minimal reproducible example for this question), a good next step could be to create a new (sub-)function out of Block 2. This subfunction then should be started assigning Block1Var (-> actual parameter) to Block2Var (-> formal parameter). If there were no other coupling to the rest of the function, one could cut the rest of Block 2 and drop it as a function definition, and would only have to replace the assignment by the subfunction call.
My answer is fairly speculative, but I have seen many cases where this strategy helped me to mark useful points to split a complex function later during the development. Of course, this interpretation only applies to an intermediate stage of development and not to code that is stated to be "ready for release".
I'm totally new to this, the task has been thrown at me as important and I've never done anything like this before. I have been given a template containing roughly this:
<apex:column headervalue="Amount"><c2g:CODAFormatterController number="{!IF([some condition],[something],[something else])}"/></apex:column>
I've replaced the statements with condition/something/something else
is there a way to use a function as you'd do in javascript, so something like
number="getNumber(x);"
or do I have to chain some IF statements together somehow? Is there an IF...ELSE?
I don't know what a CODAFormatterController is as it returned 0 results on google.
Any advice would help, I'm afraid I've been thrown in at the deep end here!
The VForce inlines are functional, they must ultimately return a value, be that a simple value or an invocation point for a piece of server side code. They do not support imperative coding and they are being resolved server-side (long before JS comes into play). in that regard the IF(condition,valuetrue,valuefalse) is an equivalent to IF..THEN..ELSE..ENDIF
You are off course free to chain any number of functions provided there is no type mismatch, meaning your valuetrue could itself be a function, including being an IF function itself.
Usually when people encounter these kind of problems there is always a workaround by using a slightly different approach. It all depends on what you are trying to do here...
I stumbled upon this question while doing some work myself on visualforce pages. Anyway, if anybody else sees this question they should know that there's no need to use the complicated nested IF statements, now there is a CASE function available in Salesforce.
Documentation - https://developer.salesforce.com/docs/atlas.en-us.198.0.pages.meta/pages/pages_variables_functions.htm
{!CASE(Opportunity.StageName,
"Prospecting", "1",
"Needs Analysis", "2",
"Proposal/Price Quote", "3",
"default val")} <!-- the last one returns if none of the previous results matched -->
I have some programs which make heavy use of libraries with enumerations of error codes.
The kind where 0(first value of enum) is success and 1 is failure. In some cases I have my own helper functions that return bool indicating error, in other cases I bubble up the error enumeration. Unfortunately sometimes I mistake one for the other and things fail.
What would you recommend? Am I missing some warnings on gcc which would warn in these cases?
P.S. it feels weird to return an error code which is totally unrelated to my code, although I guess I could return -1 or some other invalid value.
Is it a bad idea? No, you should do what makes sense rather than following some abstract rule (the likes of which almost never cater for all situations you're going to encounter anyway).
One way I avoid troubles is to ensure that all boolean-returning function read like proper English, examples being isEmpty(), userFlaggedExit() or hasContent(). This is distinct from my normal verb-noun constructs like updateTables(), deleteAccount() or crashProgram().
For a function which returns a boolean indicating success or failure of a function which would normally follow that verb-noun construct, I tend to use something like deleteAccountWorked() or successfulTableUpdate().
In all those boolean-returning cases, I can construct an easily readable if statement:
if (isEmpty (list)) ...
if (deleteAccountWorked (user)) ...
And so on.
For non-boolean-returning functions, I still follow the convention that 0 is okay and all other values are errors of some sort. The use of intelligent function names usually means it's obvious as to which is which.
But keep in mind, that's my solution. It may or may not work for other people.
In the parts of the application that you control, and the parts that make up your external API I would say, choose one type of error handling and stick to it. Which type is less important, but be consistent. Otherwise people working on your code will not know what to expect and even you yourself will scratch you head when you get back to the code in a year or so ;)
If standardizing on a zero == error scheme, you can mix and match both enum and bool if you construct your tests like this:
err = some_func();
if !err...
Since the first enum evaluates to zero and also the success case it matches perfectly with bool error returns.
However, in general it is better to return an int (or enum) since this allows for the expansion of the error codes returned without modification of calling code.
I wouldn't say, that it's a bad practice.
There's no need to create tons of enum-s, if you just need to return true/false, and you don't have other options (and true and false are explanatory enough ).
Also, if your functions are named OK, you will have less "mistakes"
For example - IsBlaBla - expects to return true. If you have [Do|On]Reload, a reload could fail for many reasons, so enum would be expected. The same for IsConnected and Connect, etc.
IMHO function naming helps here.
E.g. for functions that return a boolean value, is_foo_bar(...), or for functions that return success or an error code, do_foo_bar(...).
I only wanted to allow one instance of my C extension class to be made, so I wanted to include the singleton module.
void Init_mousetest() {
VALUE mouseclass = rb_define_class("MyMouse",rb_cObject);
rb_require("singleton");
VALUE singletonmodule = rb_const_get(rb_cObject,rb_intern("Singleton"));
rb_include_module(mouseclass,singletonmodule);
rb_funcall(singletonmodule,rb_intern("included"),1,mouseclass);
### ^ Why do I need this line here?
rb_define_method(mouseclass,"run",method_run,0);
rb_define_method(mouseclass,"spawn",method_spawn,0);
rb_define_method(mouseclass,"stop",method_stop,0);
}
As I understand it, what that line does is the same as Singleton.included(MyMouse), but if I try to invoke that, I get
irb(main):006:0> Singleton.included(MyMouse)
NoMethodError: private method `included' called for Singleton:Module
from (irb):6
from C:/Ruby19/bin/irb:12:in `<main>'
Why does rb_include_module behave differently than I would expect it to? Also any tangential discussions/explanations or related articles are appreciated. Ruby beginner here.
Also it seems like I could have just kept my extension as simple as possible and just hack some kind of interface later on to ensure I only allow one instance. Or just put my mouse related methods into a module... Any of that make sense?
according to http://www.groupsrv.com/computers/about105620.html the rb_include_module() is actually just Module#append_features.
Apparently Module#include calls Module#append_features and Module#included. So in our C code we must also call included. Since clearly something important happens there.