I could use a little advice on naming my assemblies
(ie. When to turn a logical naming convention in my
namepaces into its own DLL).
I recently downloaded an example project with a ton of
class libraries in it that almost exactly mirrored the
namespaces.
To date, I have been building one massive class
library - MyProject.DLL - and referencing it in my
project. This way, I only need one library and can
access all namespaces using it.
But, in the project I downloaded, there seems to
be a DLL for every namespace (and, in some cases,
subcategoreis within a namespaces. For example,
SomeProj.Web.Security has SomeProj.Web.Dll and
SomeProj.Web.Security.Dll).
I understand that having multiple DLLs can make
it easier to focus on particular areas of the project
(and, probably, updating the DLL withing the site
easier) but is there a best practice here?
Thanks in advance...
OK, this pretty much answers my question:
http://msdn.microsoft.com/en-us/library/ms229048.aspx
Related
I am having to do some Java work, having been immersed in .Net/C# for many years. I used to think that a Package was equivalent to a .Net assembly or dll - other SO qus that suggest this get a flat "no" - not the same, and yet the word "package" strongly suggests a packed something that could be shared around.
So, in Java, what IS the equivalent of the shareable DLL/project/assembly/class library? In .Net it is standard practice to reference another local project or a DLL built elsewhere. If I wanted to market MyWonderfulLibrary in .Net, I might deliver a DLL file. Equivalent in Java - a jar file? Is this always called an "archive"? Archive suggests something put away for safe-keeping and rarely accessed....
I'm having problems coming to terms with the terms, so to speak. Does Bean = Class? - another source of confusion...
There is a lot of info on comparing the languages, but any guidance or info that compares/clarifies common terminology in .Net projects and Java "projects" (?) would be much appreciated.
I am working on a silverlight project and I am using MEF to download xap file of other silverlight project and use its pages and functions in my main Project.
I can do the same thing using referencing dll of that project into my main project.
So I want to know what is the difference between using MEF to reusing components and Simply Adding Reference to the DLL of another project in current project? I mean that we also add reference to the project we import in our current project. Then how it is different from conventional form of component use?
Thanks,
First, we need to separate MEF and PRISM (since you used it in your tags).
MEF is primarily used to provide inversion of control (IoC). It makes it easy to manage dependencies your viewmodels and other classes to separate concerns and improve testability (amongst other benefits).
PRISM however is primarily designed for the following scenario: You don't know, what view goes into a specific container at compile time, and want ViewA for CustomerA, ViewB for CustomerB and so on. PRISM helps you to losely couple your regions and views in a way, so that the application can decide at runtime, what view will be displayed. Another scenario, is that administrators get one view, other users another etc. PRISM also has other features (like the event aggregator), but I'd say the former is the most important one.
Now, I'd say MEF is never a bad thing to use for a bigger project. But I'd only use PRISM, if you really need the functionality it provides, since it can be very limiting. If you don't, simply add the references as you explained and let MEF know about those assemblies with the AssemblyCatalog.
So for MEF, I'd suggest you learn about Depdendency Injection and IoC. I found this blogpost by Martin Fowler quite good. As for PRISM, get familiar with what it does, and decide if you really need it.
Hope this helps.
Let me complement Lue's answer on the difference between MEF and referencing dlls a bit:
The two things are orthogonal activities, meaning that if you reference a dll directly you might still want to use MEF to detect the types in it - and vice versa you might grab a specific type in a dll you dynamically loaded directly (without MEF).
MEF basically finds types in dlls according to certain criteria and has a bit of convenience stuff in it to automatically populate properties and collections with such types. It can be used to make a system more decoupled and thus more maintainable. For example, a video editing software may look for all types implementing a certain interface in all known dlls to use as filters. Whether you include the filters directly as a dll or let the user download them on demand: In both cases your application becomes slightly cleaner by using MEF, since there is no hard-coded list of filters anywhere. Still, in the presence of dynamic library loading MEF is especially useful.
I have created a number of re-usable classes that I use across xcode projects, for example:
Utility
EmailController
MarketingController
FlashLightController
etc
I had been simply copying these class files from and back into a central repository, but now I have a number of apps it is all getting a little confusing from a config management point of view. So I was looking for an alternative.
I started investigating Static Libraries but they seem to be quite a lot of more effort for simply re-using code (e.g. different libs for device vs simulator, still having to have copies of .h files, etc).
Does anyone know of a decent alternative for quick and easy code reuse?
Thanks, Charlie
You can put the code files into a project without actually copying them into the project. In other words, just keep the class files in a completely separate location. Import them into many projects, but uncheck the option to copy them in. The projects will still refer to them successfully. Now a change made in the class files will propagate to every project that uses them.
Also, consider whether workspaces will help you.
In my view, almost anything is better than making a library or framework!
Static libraries would probably be your best bet, as I have used them and have found them to be pretty easy to use. (I haven't had to use different libraries for device or simulator, mine works on them all). Having the header isn't that annoying, and static libraries are really the only way (outside of dynamic libraries, which are banned by apple) other than copying the files to reuse code.
I'm fairly new to programming and wanted to start programming more efficiently. Try as I may I often find myself straying from the MVC model.
I was wondering are there any tips or methods in keeping your code organized when coding in xcode objc? To be more specific (I know you guys like that :) I want to
Be able to write libraries or self-containing code that can bring from one project to another
Share my code with others as open sourced projects
Prevent myself from writing messy code that does not follow proper structure
Use a high warning level. Build cleanly.
Remove all static analyzer issues.
Write some unit tests.
Keep the public interfaces small.
Specify your library's dependencies (e.g. minimum SDK versions and dependent libraries).
Compile against multiple/supported OS versions regularly.
Learn to create and manage static library targets. This is all you should need to support and reuse the library in another project (unless you drag external resources into the picture, which becomes a pain).
No global state (e.g. singletons, global variables).
Be precise about support in multithreaded contexts (more commonly, that concurrency shall be the client's responsibility).
Document your public interface (maybe your private one too…).
Define a precise and uniform error model.
You can never have enough error detection.
Set very high standards -- Build them for reuse as reference implementations.
Determine the granularity of the libraries early on. These should be very small and focused.
Consider using C or C++ implementations for your backend/core libraries (that stuff can be stripped).
Do establish and specify any prefixes for your library's objc classes and categories. Use good prefixes too.
Minimize visible dependencies (e.g. don't #import tons of frameworks which could be hidden).
Be sure it compiles without the client needing to add additional #imports.
Don't rely on clients putting things in specific places, or that resources will have specific names.
Be very conservative about memory consumption and execution costs.
No leaks.
No zombies.
No slow blocking operations on the main thread.
Don't publish something until it's been well tested, and has been stable for some time. Bugs break clients' code, then they are less likely to reuse your library if it keeps breaking their program.
Study, use, and learn from good libraries.
Ask somebody (ideally, who's more experienced than you) to review your code.
Do use/exercise the libraries wherever appropriate in your projects.
Fix bugs before adding features.
Don't let that scare you -- it can be really fun, and you can learn a lot in the process.
There are a number of ways you can reuse code:
Store the code in a common directory and include that directory in your projects. Simple, but can have versioning issues.
Create a separate project which builds a static iOS library and then create a framework. More complex to setup because it involves scripting to build the framework directory structure. But easy to use in other projects and can handle versioning and device/simulator combined libs.
Create a separate project which builds a static iOS library and then include this as a subproject in other projects. Avoids having to build frameworks and the results can be more optimised.
That's the basic 3, there are of course a number of variations on these and how you go about them. A lot of what you decide to do is going to come down to who you are going to do this for. For example I like sub projects for my own code, but for code I want to make available for others, I think frameworks are better. even if they are more work to create. Plus I can then wrap them up with docsets of the api documentation and upload the whole lot as a DMG to github for others to download.
I have an application that uses many different .NET managed DLL's as objects (each DLL implements a common interface). Each DLL also has a version number in the file name.
Suppose I create the object "Shape~01.dll." The application will use that DLL but it can't be replaced while the application is running. So, if I want to "upgrade" the shape dll I have to create "Shape~02.dll" and the application has to dynamically search for and load the newest dll everytime a shape is created and/or the user has to restart the application. It get's worse, each dll depends on the main .exe thus has to be rebuilt with the main .exe.
Is there an easier method to have dynamically "replaceable" objects?
Well, this isn't the best solution (still thinking about it), but you can unload dll files which will allow them to be replaced. That might be a quick stopgap solution until you come up with a better idea.
You don't mention which language/platform you are trying to accomplish this in, so I will answer for the .NET Framework.
If you want to do it the hard way look at Shadow Assemblies, this is the method that ASP.NET uses to keep the site updateable though it is using the files.
For a much easier method look at the new System.Addin namespace, this uses Shadow Assemblies under the hood and should do what you want.
Instead of polling when creating an object, why not just request notification from the system when the file system changes?
The class is System.IO.FileSystemWatcher in.NET.
For native code there are a few ways to watch a folder, but IANAND (I am not a native developer ;).
Although having said those things, you probably want to rethink the reason you need to change your objects so frequently, because it will probably take a lot of work to make it work.
You used the dynamic tag, so maybe you should try a dynamic language? :)