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Pete O'Hanlon wrote: with a torch
Or maybe just an ear-trumpet? 
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Was that a brainless question? 
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Not completely, but it's more a Lounge type discussion, than a technical question.
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Oh that explains the hatred towards my question. But I was not trying to degrade that article. All I meant about the technical aspects of that idea. Sorry for my ignorance; I thought my solution can overcome the problem specified in the article.
Thanks,
Pop
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I think the "hatred" was directed at Uncle Bob, not at you.
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Thank you! 
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Was there hatred towards your article? I was actually commenting that o' Uncle Bob seemed to have pulled his argument out of his posterior.
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Hi,
Thank you for the blog link.
You propose what is called mixin, which is really the go to solution to avoid bloated inheritance hierarchies.
The good thing about mixin of Subject is that you hide functionality and avoids to duplicate the code in Subject.
The bad thing is that you still need to duplicate the code that calls Subject aka relaying.
DI with mixin is also good since you make the dependency known to the outside. This opens up for implementation replacement from the outside and gives better transparency.
However, Uncle Bob really wants to hide stuff and use inheritance to avoid ANY code duplication and he can't do that in a single inheritance language.
I love interfaces because they form a specification layer without any implementation details. I love abstract classes because they can be implementation templates for concrete classes. I do not want to mix the 2 concerns - at all. And it IS a tad annoying when you need add mixin in you abstract classes to avoid code duplication.
I wouldn't mind multiple inheritance, if the language/compiler could manage diamonds in a consistent and obvious way (No, C++ doesn't). The class hierarchy is however implementation - not specification (IMHO). Uncle Bob doesn't address that view on the interface keyword.... and I am not sure the interface keyword had that view in mind when invented.
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Keld Ølykke wrote: No, C++ doesn't
I think it does. Why do you say it doesn't?
Keld Ølykke wrote: class hierarchy is however implementation - not specification
Agreed. Hence, I don't think interfaces are "harmful", but what Uncle Bob was really complaining about is not being able to have multiple base classes.
However, I think true separation of concerns would use neither DI nor inheritance to do his observer pattern but rather a separate "observer manager" class that does both the observing and registration/deregistration.
#SupportHeForShe If your actions inspire others to dream more, learn more, do more and become more, you are a leader.-John Q. Adams
You must accept 1 of 2 basic premises: Either we are alone in the universe or we are not alone. Either way, the implications are staggering!-Wernher von Braun
Only 2 things are infinite, the universe and human stupidity, and I'm not sure about the former.-Albert Einstein
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Well, by not consistent I mean that you can end up with compiler accepted code, but it is unknown what it will do. The "dreaded diamond" refers to the situation where class C inherits from 2 classes B1 & B2 that both inherits the same base A. C will have 2 copies of all fields from A and at runtime it is undefined which copy you address.
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Ah, sure, I see. But you can solve that by using "virtual" inheritance. Then there's only one instance of A. Of course, you can't always do that when using third-party libraries.
#SupportHeForShe If your actions inspire others to dream more, learn more, do more and become more, you are a leader.-John Q. Adams
You must accept 1 of 2 basic premises: Either we are alone in the universe or we are not alone. Either way, the implications are staggering!-Wernher von Braun
Only 2 things are infinite, the universe and human stupidity, and I'm not sure about the former.-Albert Einstein
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Yes. If C++ was a game I would call it a tad unforgiving
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this question is logical type. there is single data centre with single firewall and to handle 5 lakh clients from this single data centre i want a technique in which i dont have to mess any thing with data centre but infact some kind of delay must be generated at clients side only in order to avoid load or traffic on data centre
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Impossible. How can client systems know when to delay and when it is OK to connect? If your system cannot be tuned to handle large load then you need to employ a network engineer to help you.
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Can somebody explains how I can implement properly Open/Close principles in Python? Since Python class does not supports method overloading or function overloading like in C++, C# or Java. In. e.x.:
if I created class which calls connectivity:
class Connectivity(object):
def connect(self, ip, port):
and later If i want to add connection time out argument for connection method I cannot keep Open/Close principles like this:
class Connectivity(object):
def connect(self, ip, port):
def connect(self, ip, port, timeout):
So what I should do in this case? How I can follow properly SOLID principles in Python? Thank you in advance.
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Disclaimer; I have never touched Python.
If C# had no function overloading I'd be passing an object, as opposed to a list of parameters. For example;
class ConnectArgs
{
public object self { get; set; }
public string ip { get; set; }
public int port { get; set; }
}
class ConnectArgsExt: ConnectArgs
{
public int TimeOut { get; set; }
}
With the method accepting it like below;
public connect(ConnectArgs args)
Since you defined a class, I assume Python has classes and supports inheritance. That way you needn't change the interface, but you'd still have the option to extend it with a new parameter if required.
Bastard Programmer from Hell 
If you can't read my code, try converting it here[^]
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You need to create a new method with a different name, or, better still, a new class that inherits from this class. You can then override the method, but still call the base method if necessary. Something like:
class Connectivity(object):
def connect(self, ip, port):
class NewConnectivity(Connectivity):
def connect(self, ip, port, timeout):
Connectivity(self, ip, port)
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Of course, the simplest way is to add the timeout as an optional parameter thus:
class Connectivity(object):
def connect(self, ip, port, timeout = 0):
x = Connectivity()
x.connect(ip, port)
x.connect(ip, port, 30)
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i dont know anything about programming or designs but i want them to make a system in short it accepts documents PDF or word doc from various companies and they all arrive at our server, currently we are now manually selecting then printing each page, so my question is what technologies needed to make the process of making the arrived documents to be auto printed then saved in a database and then each document gets our company stamp on top of each paper + we want each document to have different barcode different serial number then the other documents. am doing the process manually on photoshop taking the company stamp and placing it on top of each paper but we didnt do the barcode method yet
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Whay you posted is an explanation. Maybe not a very detailed one, but details would distract from the general idea you're conveying.
I'd first recommend to divide this into multiple (!) smaller projects; it'll be easier to handle. Receiving documents and putting them into a database should be relative easy. Stamping each document will be a lot harder - there's some readonly formats, and a password-protected Word file might be hard to modify. If the files are in a database, then another application can fetch those (independently of the rest of the apps) and prnt them (once!).
There's a four-part series on Joel that can help with creating specs[^].
Bastard Programmer from Hell
If you can't read my code, try converting it here[^]
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If you're explaining the requirements to your developers then you don't need to worry about the details of implementation. Let them worry about that. What you need to do is document in as much detail as you can, and as clearly as you can, what you need the application to do. Think in terms of inputs and outputs.
Once you have documented your requirements, then pass this document to your development team to implement.
"There are two ways of constructing a software design: One way is to make it so simple that there are obviously no deficiencies, and the other way is to make it so complicated that there are no obvious deficiencies. The first method is far more difficult." - C.A.R. Hoare
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Member 11331225 wrote: How can i explain this to our programmers?
Just like you did. They would/should then ask you questions to clarify it.
For starters how exactly does the following happen "accepts documents PDF or word doc from various companies".
Member 11331225 wrote: and then each document gets our company stamp on top of each paper
Just to be clear...that sounds a bit suspect in terms of copyright. If the documents are originating from another company then you are bound by their terms of usage. You don't get to arbitrarily alter them unless it is within acceptable usage parameters. Not saying that you can't do this just why.
Might also note that this requirement - adding something to each page is going to make the project more complex.
And why do you need to print them at all?
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I am currently working on a store search function. The search criteria are quite complex, for example:
Footage >= 50 AND (SizeCode == SizeType.Large OR MobileEnd == "ABC")
I think that each criterion could be represented by a Func<store, boot> (I am using C# and LINQ).
Func<Store, bool> filter1 = (s => s.Footage >= 50);
Func<Store, bool> filter2 = (s => s.MobileEnd =="abc");
Func<Store, bool> filter3 = (s => s.SizeCode == SizeType.Large);
My question is how I can deal with AND, OR, NOT logic, and order of precedence. How can I convert the user input into a LINQ expression?
Thanks.
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