I'm currently working on a flutter application. I have a file with a big widget tree. In order to easier understand, read and maintain I wanted to "crop" the widget tree.
First what I did was to create multiple functions, which represented a bigger part of the tree such as _createFancyImage() or _createFancyContainer. After some research, I found out that such a design has some downsides (see: https://github.com/flutter/flutter/issues/19269). So then I decided to create StatelessWidgets instead. Because of the huge size of the widget tree, I broke it down to 3 logical StatelessWidgets. Now I can use FancyImage() or FancyContainer() which represent each a standalone widget.
As a beginner, I'm not sure whether I should keep those StatelessWidgetclasses within the same file. Alternatively, I could create independent files. One thing to clarify: I'm not using those fancy widgets somewhere else. Those are unique to this one big widget tree otherwise I could have outsourced them into a new folder such as "common_widgets" or "components".
Unfortunately, I couldn't find something within the Dart and Flutter Repo style guides nor on the internet.
I appreciate every suggestion.
You can add as much classes as you need in a single file. It depends on the developer's mindset.
But, let say if one of your class can be reused by other classes or packages then you should add it to another file for better separation.
I can favour you one approach is that your each file should have maximum one Stateful widget and as many Stateless widgets as you want for that corresponding widget will be a better scenario.
Still in some cases if you feel that more than enough stateless widgets has been added in a single file you should separate it in another file based on your choice.
I prefer to keep one public widget which having the same name as the filename and remaining private widgets.
comming to your ques is How many widgets in a single file?
Its actually depend there is no such rule to restrict the limit of file. Different authors having different preference. I prefer try to keep 5-6 classes(widgets) and
each one having 5-6 functions.
Try to make a file single responsible i.e(5-6 classes together responsible for single functionality). Don't make god class which having unrelated concerns together later it will pains(haha)
If it's a common widget keep them separate to respect DRY principle(Don't repeat yourself)
If the widget is further divided into 3-4 widgets or it children widget change depend upon rest response keep seprate for good practise
Bonus Tip: try using code folding shortcuts to push a little more
I have been investigating the inline styles & templates vs externals in the new Angular 2 components.
I was wondering what is the recommended route. I know it doesn't matter as far as functionality is concerned.
Having styles and templates together in the component reminds me of how reactjs tackles things. It does have its advantages.
Code Completion etc? Is this better for inline vs external? I am unsure which route to take or which is recommended.
I think it's about encapsulation and uniqueness of the component. Sometime you run into situation where certain elements require some special styles. With the traditional css, you would create a unique class, sometimes use !important to make sure it applies....
with ng components, your component can share global style and at the same time have it's own unique styles. Furthermore, component's styles can be contain within itself and/or share globally, given you more flexibility to do what you want.
https://egghead.io/lessons/angular-2-controlling-how-styles-are-shared-with-view-encapsulation?series=angular-2-fundamentals
From https://angular.io/styleguide
Extract Template and Styles to Their Own Files
Style 05-04
Do extract templates and styles into a separate file, when more than 3
lines.
Do name the template file [component-name].component.html, where
[component-name] is our component name.
Do name the style file [component-name].component.css, where
[component-name] is our component name.
Why? Syntax hints for inline templates in (.js and .ts) code files are
not supported by some editors.
Why? A component file's logic is easier to read when not mixed with
inline template and styles.
Ui:include and xhtml based tag (the one with source elt) seem to be much the same for me. Both allow to reuse piece of markup. But I believe there should be some reason for having each. Could somebody please briefly explain it? (I guess if I read full facelets tutorial I will learn it, but I have not time to do it now, so no links to lengthy docs please :)
They are quite similar. The difference is mainly syntactical.
After observing their usage for some time it seems the convention is that fragments that you use only in a single situation are candidates for ui:include, while fragments that you re-use more often and have a more independent semantic are candidates for a custom tag.
E.g.
A single view might have a form with three sections; personal data, work history, preferences. If the page becomes unwieldy, you can divide it into smaller parts. Each of the 3 sections could be moved to their own Facelet file and will then be ui-include'ed into the original file.
On the other hand, you might have a specific way to display on image on many views in your application. Maybe you draw a line around it, have some text beneath it etc. Instead of repeating this over and over again you can abstract this to its own Facelet file again. Although you could ui:include it, most people seem to prefer to create a tag here, so you can use e.g. <my:image src="..." /> on your Facelets. This just looks nicer (more compact, more inline with other components).
In the Facelets version that's bundled with JSF 2.0, simple tags can be replaced by composite components. This is yet a third variant that on the first glance looks a lot like custom tags, but these things are technically different as they aren't merely an include but represent true components with declared attributes, ability to attach validators to, etc.
I have always viewed tags as completely different than the normal folder hierarchy model. I am building a system that needs tagging to tag sets of data. We had the db design all worked out, (pretty straightforward model) but a debate arose around the value of still having concepts of hierarchies within a world of tags.
On SOF, as an example, the only equivalent I see some of this by using - in some tag names like tagging; jquery, jquery-ui, jquery-ui-dialog so there is no inherent modeled relationship (just a naming convention).
Is there any conventional wisdom of best practices around how and if hierarchies should exist in a world of tagging?
I developed a portal that involved hierarchical tags. I can assure you that is a mess to manage :)
My solution then moved to a hybrid approach in which tags can be stand-alone or hiearchically handled but they reside in two different namespaces.
This because some tags can be seen as children of parents of other tags while others cannot, so for example dialog tag is a concept that is also indipendent from jquery so a content with both tags jquery dialog has implicitly the relationship needed.
Hierarchical should be used to express a kind of inheritance between concepts, eg. collections -> trees, lists, maps in which trees tag can be effectively included inside a collections tag.
In your example dialog and jquery are orthogonal and uncomparable, so it makes no sense to make one child of another.
The names "jquery", "jquery-ui", "jquery-ui-dialog" aren't tags, but the equivalent of file structure paths, hierarchical by nature.
If your data is easy to authoritatively categorize then present it as a tree. If users only see a few of their own tags (like in Gmail), you could make it possible to sort and nest the tag list and save that structure per user, separately from tags themselves. If there are great many tags with power distribution of content (for example if 10% of tags describe 90% of content) then a tag cloud can help.
In short, it depends on the data.
hierarchies have in general a disadvantage compared to sets.
think of bookmarks and tag-bundles like delicious.com.
i prefer to search for a set using sport and newer-than-1-week and ( english-language or chinese-language ) and not ( soccer or boxing ).
I used to have one class for one file. For example car.cs has the class car. But as I program more classes, I would like to add them to the same file. For example car.cs has the class car and the door class, etc.
My question is good for Java, C#, PHP or any other programming language. Should I try not having multiple classes in the same file or is it ok?
I think you should try to keep your code to 1 class per file.
I suggest this because it will be easier to find your class later. Also, it will work better with your source control system (if a file changes, then you know that a particular class has changed).
The only time I think it's correct to use more than one class per file is when you are using internal classes... but internal classes are inside another class, and thus can be left inside the same file. The inner classes roles are strongly related to the outer classes, so placing them in the same file is fine.
In Java, one public class per file is the way the language works. A group of Java files can be collected into a package.
In Python, however, files are "modules", and typically have a number of closely related classes. A Python package is a directory, just like a Java package.
This gives Python an extra level of grouping between class and package.
There is no one right answer that is language-agnostic. It varies with the language.
One class per file is a good rule, but it's appropriate to make some exceptions. For instance, if I'm working in a project where most classes have associated collection types, often I'll keep the class and its collection in the same file, e.g.:
public class Customer { /* whatever */ }
public class CustomerCollection : List<Customer> { /* whatever */ }
The best rule of thumb is to keep one class per file except when that starts to make things harder rather than easier. Since Visual Studio's Find in Files is so effective, you probably won't have to spend much time looking through the file structure anyway.
No I don't think it's an entirely bad practice. What I mean by that is in general it's best to have a separate file per class, but there are definitely good exception cases where it's better to have a bunch of classes in one file. A good example of this is a group of Exception classes, if you have a few dozen of these for a given group does it really make sense to have separate a separate file for each two liner class? I would argue not. In this case having a group of exceptions in one class is much less cumbersome and simple IMHO.
I've found that whenever I try to combine multiple types into a single file, I always end going back and separating them simply because it makes them easier to find. Whenever I combine, there is always ultimately a moment where I'm trying to figure out wtf I defined type x.
So now, my personal rule is that each individual type (except maybe for child classes, by which a mean a class inside a class, not an inherited class) gets its own file.
Since your IDE Provides you with a "Navigate to" functionality and you have some control over namespacing within your classes then the below benefits of having multiple classes within the same file are quite worth it for me.
Parent - Child Classes
In many cases i find it quite helpful to have Inherited classes within their Base Class file.
It's quite easy then to see which properties and methods your child class inherits and the file provides a faster overview of the overall functionality.
Public: Small - Helper - DTO Classes
When you need several plain and small classes for a specific functionality i find it quite redundant to have a file with all the references and includes for just a 4-8 Liner class.....
Code navigation is also easier just scrolling over one file instead of switching between 10 files...Its also easier to refactor when you have to edit just one reference instead of 10.....
Overall breaking the Iron rule of 1 class per file provides some extra freedom to organize your code.
What happens then, really depends on your IDE, Language,Team Communication and Organizing Skills.
But if you want that freedom why sacrifice it for an iron rule?
The rule I always go by is to have one main class in a file with the same name. I may or may not include helper classes in that file depending on how tightly they're coupled with the file's main class. Are the support classes standalone, or are they useful on their own? For example, if a method in a class needs a special comparison for sorting some objects, it doesn't bother me a bit to bundle the comparison functor class into the same file as the method that uses it. I wouldn't expect to use it elsewhere and it doesn't make sense for it to be on its own.
If you are working on a team, keeping classes in separate files make it easier to control the source and reduces chances of conflicts (multiple developers changing the same file at the same time). I think it makes it easier to find the code you are looking for as well.
It can be bad from the perspective of future development and maintainability. It is much easier to remember where the Car class is if you have a Car.cs class. Where would you look for the Widget class if Widget.cs does not exist? Is it a car widget? Is it an engine widget? Oh maybe it's a bagel widget.
The only time I consider file locations is when I have to create new classes. Otherwise I never navigate by file structure. I Use "go to class" or "go to definition".
I know this is somewhat of a training issue; freeing yourself from the physical file structure of projects requires practice. It's very rewarding though ;)
If it feels good to put them in the same file, be my guest. Cant do that with public classes in java though ;)
You should refrain from doing so, unless you have a good reason.
One file with several small related classes can be more readable than several files.
For example, when using 'case classes', to simulate union types, there is a strong relationship between each class.
Using the same file for multiple classes has the advantage of grouping them together visually for the reader.
In your case, a car and a door do not seem related at all, and finding the door class in the car.cs file would be unexpected, so don't.
As a rule of thumb, one class/one file is the way to go. I often keep several interface definitions in one file, though. Several classes in one file? Only if they are very closely related somehow, and very small (< 5 methods and members)
As is true so much of the time in programming, it depends greatly on the situation.
For instance, what is the cohesiveness of the classes in question? Are they tightly coupled? Are they completely orthogonal? Are they related in functionality?
It would not be out of line for a web framework to supply a general purpose widgets.whatever file containing BaseWidget, TextWidget, CharWidget, etc.
A user of the framework would not be out of line in defining a more_widgets file to contain the additional widgets they derive from the framework widgets for their specific domain space.
When the classes are orthogonal, and have nothing to do with each other, the grouping into a single file would indeed be artificial. Assume an application to manage a robotic factory that builds cars. A file called parts containing CarParts and RobotParts would be senseless... there is not likely to be much of a relation between the ordering of spare parts for maintenance and the parts that the factory manufactures. Such a joining would add no information or knowledge about the system you are designing.
Perhaps the best rule of thumb is don't constrain your choices by a rule of thumb. Rules of thumb are created for a first cut analysis, or to constrain the choices of those who are not capable of making good choices. I think most programmers would like to believe they are capable of making good decisions.
The Smalltalk answer is: you should not have files (for programming). They make versioning and navigation painful.
One class per file is simpler to maintain and much more clear for anyone else looking at your code. It is also mandatory, or very restricted in some languages.
In Java for instance, you cannot create multiple top level classes per file, they have to be in separate files where the classname and filename are the same.
(C#) Another exception (to one file per class) I'm thinking of is having List in the same file as MyClass. Where I envisage using this is in reporting. Having an extra file just for the List seems a bit excessive.