What is the proper way to name my revisions?
v1.0.3.20 Alpha
or
Alpha v1.0.3.20
There isn't really any "proper" way. While most people use the dot pattern "x.x.x", it isn't necessarily the proper way to do it. Likewise with your question, it is up to you.
I would suppose that the former is more natural to say, and I would prefer it, but it doesn't really matter either way.
You have two pieces of information there: version number and release state/quality. The two might be tied together, but don't have to be. For example, you could have multiple "releases" for a single version number: v1.1-alpha, v1.1-beta, v1.1-final, and so forth; or you could break those down into individual numbers: v1.0.1-alpha, v1.0.2-beta, v1.1.0-final; or something entirely different!
This is really a question of branding more than anything; due to the wide interpretation of version info across different products, you already have to know how each different product uses them to make sense of it. Of course, if you're contributing to, working with, or emulating another project: do what they do. It'll be simpler and lead to less confusion.
As used in my examples, I'd prefer "n.n...-quality", but it's only syntax.
Related
I don't understand this issue:
Issue: HIS Metriken - Cyclomatic (CR-MET4): [function_name] 13>10
It appears in Klocwork analysis while checking the issues of Code: METRICS.E.HIS_Metriken___Cyclomatic__CR_MET4_
Can anyone support?
Thanks
Do you see all those ifs, elses, loops in that function?
Those are the problem, you need to either design this function's logic more elegantly or split it into more functions with well-defined purposes.
By the way, I can only see that problematic function of yours because I am especially clairvoyant. For this kind of question you should normally show your code, just to be fair towards all those other users which cannot read your mind like I did.
Naaa, not really. The cyclomatic complexity is a measure for number of potential paths through your function. And that you have crossed the treshold of 10 by 3 means your function must be full of control structs, which create many paths.
I am learning Ruby, reading few books, tutorials, foruns and so one... so, I am brand new to this.
I am trying to develop a stock system so I can learn doing.
My questions are the following:
I created the following to store transactions: (just few parts of the code)
transactions.push type: "BUY", date: Date.strptime(date.to_s, '%d/%m/%Y'), quantity: quantity, price: price.to_money(:BRL), fees: fees.to_money(:BRL)
And one colleague here suggested to create a Transaction class to store this.
So, for the next storage information that I had, I did:
#dividends_from_stock << DividendsFromStock.new(row["Approved"], row["Value"], row["Type"], row["Last Day With"], row["Payment Day"])
Now, FIRST question: which way is better? Hash in Array or Object in Array? And why?
This #dividends_from_stock is returned by the method 'dividends'.
I want to find all the dividends that were paid above a specific date:
puts ciel3.dividends.find_all {|dividend| Date.parse(dividend.last_day_with) > Date.parse('12/05/2014')}
I get the following:
#<DividendsFromStock:0x2785e60>
#<DividendsFromStock:0x2785410>
#<DividendsFromStock:0x2784a68>
#<DividendsFromStock:0x27840c0>
#<DividendsFromStock:0x1ec91f8>
#<DividendsFromStock:0x2797ce0>
#<DividendsFromStock:0x2797338>
#<DividendsFromStock:0x2796990>
Ok with this I am able to spot (I think) all the objects that has date higher than the 12/05/2014. But (SECOND question) how can I get the information regarding the 'value' (or other information) stored inside the objects?
Generally it is always better to define classes. Classes have names. They will help you understand what is going on when your program gets big. You can always see the class of each variable like this: var.class. If you use hashes everywhere, you will be confused because these calls will always return Hash. But if you define classes for things, you will see your class names.
Define methods in your classes that return the information you need. If you define a method called to_s, Ruby will call it behind the scenes on the object when you print it or use it in an interpolation (puts "Some #{var} here").
You probably want a first-class model of some kind to represent the concept of a trade/transaction and a list of transactions that serves as a ledger.
I'd advise steering closer to a database for this instead of manipulating toy objects in memory. Sequel can be a pretty simple ORM if used minimally, but ActiveRecord is often a lot more beginner friendly and has fewer sharp edges.
Using naked hashes or arrays is good for prototyping and seeing if something works in principle. Beyond that it's important to give things proper classes so you can relate them properly and start to refine how these things fit together.
I'd even start with TransactionHistory being a class derived from Array where you get all that functionality for free, then can go and add on custom things as necessary.
For example, you have a pretty gnarly interface to DividendsFromStock which could be cleaned up by having that format of row be accepted to the initialize function as-is.
Don't forget to write a to_s or inspect method for any custom classes you want to be able to print or have a look at. These are usually super simple to write and come in very handy when debugging.
thank you!
I will answer my question, based on the information provided by tadman and Ilya Vassilevsky (and also B. Seven).
1- It is better to create a class, and the objects. It will help me organize my code, and debug. Localize who is who and doing what. Also seems better to use with DB.
2- I am a little bit shamed with my question after figure out the solution. It is far simpler than I was thinking. Just needed two steps:
willpay = ciel3.dividends.find_all {|dividend| Date.parse(dividend.last_day_with) > Date.parse('10/09/2015')}
willpay.each do |dividend|
puts "#{ciel3.code} has approved #{dividend.type} on #{dividend.approved} and will pay by #{dividend.payment_day} the value of #{dividend.value.format} per share, for those that had the asset on #{dividend.last_day_with}"
puts
end
I have been asked in an interview how one can return more than one value from function. I have answered saying by using pointers we can achieve(call by reference) this in C. Then he told me he is looking for some other way of returning more than one value. I said we can return a struct object but here also he didn't seem to be impressed.
I would like to know others ways to return more than one value from a function.
I have seen this questions being asked here on SO, but could not find anything C specific.
The tricky problem is that the interviewer has some solution they are particularly happy with in mind and they are likely grading you by whether you have the same clever trick as them or not.
You could just name a few ways such as you did, and still not fall upon their secret trick. And if you knew their secret trick, you could well not be impressed with it.
So in these situations, its to turn it from interview into conversation. Once you detect you're not moving towards their ego, you can avoid heading towards the intimidating "I don't know" "I give up" and instead try out the "so do you have any clever solution? Is there an in-house recipe for this at Xyz Inc?" etc.
Any glimpse at their obviously self-impressed solution and you are back on firm ground where you can talk about it and ask them if they have thought about various factors that come to mind and basically interview them.
Everyone loves a good listener, and getting them to talk about their tricks is a good way to get them to leave the interview throughly impressed with you! ;)
There are a few ways:
Return value using the return statement (as you already know)
Return via references.
Return values via the heap.
Return values via global variables.
That depends on what you consider a value. If a value is a piece of information for you, more values could be a struct of values. More values could be also passed via pointers or arrays, even a char* containing a list of (non-zero alphanumerical) values. If you consider a value to be a bit of information a single returned uint32_t may hold 32 values. You could even mess around with signals or sockets or pipes or files.
But for you do not even know the use case and the requirements it imposes on the solution, it's indeed a rather hard task to come up with the right solution (and you actually did come up with some proper solutions ...).
Return a pointer to a structure, or pack several small datatypes into one large datatype, or use global variables.
The first is probably the cleanest way to do it, the other two might have their uses in certain situations.
If we pass the address instead of the true value of the parameters.
Then whenever we refer those parameters we do it with the address.
returning a pointer to structure is the suitable answer.(Obviously, the objective of the program can decide what's the best that can be done). The interviewer might have wanted you to say 'I don't know' which would have shown your lack of confidence in the field. I think you provided good solutions, though not what he had in his mind. You could have asked him about a typical scenario where he wanted multiple values to be returned and then discuss how struct-pointer is a reasonable alternative.
I have question relating to implementation of arrays with Java+ANTLR combo. (I'm mainly talking about java/c style arrays).
So basically I'm asking how do you implement such feature, if there is such example already available or if someone could point me to anything that may point to solve it.
On other hand, I've searched a bit how would possible solution be. Main problem that I see
is that user may create arrays of various dimensions, even go crazy if he or she wants (like creating 5 dimension arrays or worse).
While grammar for something like this is fairly simple, like
new ID (INT (',' INT)* )
back end really gets involved a bit. As I said, user may input any number of dimensions, so array dimensions should be dynamically created. (at least as I see it, maybe I'm over complicating things?)
After searching I did found something that pretty much solves this problem perfectly, here is link to the question:
Is it possible to dynamically build a multi-dimensional array in Java?
Of course, my question is, is this viable example, it is a bit (to say at least), complicated? Is there more elegant solution to it?
Having that in mind, I was thinking maybe answer might be in the grounds of somehow transforming multidimensions
into more linear structure ? Could something like that be useful ? Simple search on stackoverflow pointed many solutions
to this, like:
Algorithm to convert a multi-dimensional array to a one-dimensional array
Would it be worth to search in that direction ?
Now, at the end, having in mind that arrays are really common feature in many languages, I must find it surprising that after searching ANTLR mailing list there is no similar question, which as I previously said leads me to believe that I'm maybe over complicating things ? (Unless I really suck at search?) I would really appreciate feedback.
Your syntax, if I'm not mistaken, corresponds to something like
new char 4,5,6,7
which is kind of strange. I expect that you really meant
new char[4,5,6,7]
However from a purely syntactic point of view, there's no reason not to just store the indices in an array and let the semantic analysis pass worry about it.
(this is a C-like environment) Say I have two instance objects, a car and a bodyShop. The car has a color iVar and corresponding accesors. The bodyShop has a method named "paintCar" that will take in a car object and change its color.
As far as implementation, in order to get the bodyShop to actually be able to change a car object's color, I see two ways to go about it.
Use the "&" operator to pass in a pointer to the car. Then the bodyShop can either tell the car to perform some method that it has to change color, or it can use the car's accessors directly.
Pass in the car object by value, do the same sort of thing to get the color changed, then have the method return a car object with a new color. Then assign the original car object to the new car object.
Option 1 seems more straightforward to me, but I'm wondering if it is in-line with OOP best practices. In general for "maximum OOP", is the "&" operator good or bad? Or, maybe I'm completely missing a better option that would make this super OOPer. Please advise :)
Option 1 is prefered:
The bodyShop can either tell the car
to perform some method that it has to
change color, or it can use the car's
accessors directly.
Even better still...create an IPaintable interface. Have Car implement IPaintable. Have BodyShop depend on IPaintable instead of Car. The benefits of this are:
Now BodyShop can paint anything that implements IPaintable (Cars, Boats, Planes, Scooters)
BodyShop is no longer tightly coupled to Car.
BodyShop has a more testable design.
I would assume that the responsibility of the bodyShop is to modify car objects, so #1 seems like the right way to go to me. I've never used a language where the "&" operator is necessary. Normally, my bodyShop object would call car.setColor(newColor) and that would be that. This way you don't have to worry about the rest of the original car's attributes, including persistence issues - you just leave them alone.
Since you're interested in the best OOP practice, you should ignore the performance hit you get with option 2. The only things you should be interested in is do either option unnecessarily increase coupling between the two classes, is encapsulation violated and is identity preserved.
Given this, option 2 is less desirable since you can't determine which other objects are holding references to the original car or worse, contain the car. In short you violate the identity constraint since two objects in the system may have different ideas of the state of the car. You run the risk of making the overall system inconsistent.
Of-course your particular environment may avoid this but it certainly would be best practice to avoid it.
Last point, does your bodyShop object have state; behaviour and identity? I realise that you have explained only the minimum necessary but possibly the bodyShop isn't really an object.
Functional v OO approaches
As an interesting aside, option 2 would close to the approach in a functional programming environment - since state changes are not allowed, your only approach would be to create a new car if it's colour changed. That's not quite what you're suggesting but it's close.
That may sound like complete overkill but it does have some interesting implications for proving the correctness of the code and parallelism.
Option 1 wins for me. The & operator is implicit in many OO languages (like Java, Python etc). You don't use "passing by value" in that languages often - only primitive types are passed in that way.
Option 2 comes with multiple problems: You might have a collection of cars, and some function unaware of it might send a car to bodyShop for painting, receive new car in return and don't update your collection of cars. See? And from more ideologic point of view - you don't create new object each time you want to modify it in real world - why should you do so in virtual one? This will lead to confusion, because it's just counterintuitive. :-)
I am not sure what this "C-like environment" mean. In C, you need this:
int paintCar(const bodyShop_t *bs, car_t *car);
where you modify the contents pointed by car. For big struct in C, you should always pass the pointer, rather than the value to a function. So, use solution 1 (if by "&" you mean the C operator).
I too agree with the first 1. I can't say it's best practice because i'm never really sure what best practice is in other peoples minds... I can tell you that best practice in my mind is the most simple method that works for the job. I've also seen this aproach taken in the hunspell win api and other c-ish api's that i've had to use. So yea i agree with scott.
http://hunspell.sourceforge.net/
//just in-case your interested in looking at other peoples code
It depends on whether the body shop's method can fail and leave the car in an indeterminate state. In that case, you're better off operating on a copy of the car, or a copy of all relevant attributes of the car. Then, only when the operation succeeds, you copy those values to the car. So you end up assigning the new car to the old car within the body shop method. Doing this correctly is necessary for exception safety in C++, and can get nasty.
It's also possible and sometimes desirable to use the other pattern - returning a new object on modification. This is useful for interactive systems which require Undo/Redo, backtracking search, and for anything involving modelling how a system of objects evolves over time.
In addition to other optinions, option 1 lets paintCar method return a completion code that indicates if the car has changed the color successfully or there were problems with it