I am creating a database library for Altium.
For example, I have several NPN transistors in the same SOT-23-3 package, but they have different pinouts: collectors and emitters are swapped.
In Celestial Altium Library different footprints are used for different manufacturers, in which there are already different pinouts. But because of this, there are several identical footprints (excluding pinouts).
What should I do in such a case? Create a new footprint or symbol? Or maybe there is a way to set the mapping in the database itself?
Related
I've been reading a lot about Entity Frameworks and now I want to implement it on my game. An Entity Framework is based on making the game entities simple containers of Components, where a Component contains a certain characteristic of an Entity (and all the variables/accessors which describe this characteristic).
The game logic is then modularized by creating Systems. Each System implements and runs a certain aspect of the game logic (eg. Collisions, Rendering, Animation). Each System has to be able to access every Entity which has some certain combination of Components (eg. RenderSystem has to get only Entities which have PositionComponent and AnimationComponent).
My question regards the best data structure for achieving such functionality.
My current idea is to create a Vector (with N cells, where N is the number of possible components) of List of Entity. So whenever I create (instantiate and add certain Components) an Entity, I would also reference this Entity from each List for each Component it contains. "Killing" an Entity would require removing each reference from each List. The problem would be querying which entities have to be processed by a certain System, because the search-key would be a combination of Components, and not a single Component, adding overhead to the operation (many searches and comparisons would have to be done).
Is my idea good? Is there any better data structure I can use? Note that everything in the game is supposed to be an Entity, summing up to thousands of Entites on a single Level (I could possibly use some space partitioning).
They are two ways of doing it,
The purely data oriented system would lead you not to have an Entity class but just components sharing an ID. In this case, a vector or a hashmap for every system wouldn't be a problem as the search in these data structure is fast. If you want several components per system per entity you can aggregate your components in one data structure adapted for each system.
The problem is that a pure data oriented system can be less usable than a more pragmatic approach where you keep all the features of the previously described system but you keep an entity class that holds reference to his components (or aggregated components structures) of every system. Processing an entity (deleting or inspecting it) becomes much easier as you still have a place where all the information about what the entity is, i.e. what it is made of and not what state it is in, can be found in one place instead of querying every system.
In your case, the best thing is to try... It's quite easy and fast to implement a rough engine in the two ways, and once you've played with the two you'll be able to decide which one suites you better.
This article is valuable as far as it suggests 4 iterations for the data structure, but no one is a good solution in my opinion. But I recommend to read it, because there is a detailed analysis of the problem, nice estimations in terms of memory and such other good material.
I have a package with a lot of classes, and I want to organize them. I would happily split them into several packages based on my "category" of class, but unfortunately most of them are parts of a united system with package-level visibility.
Is there any way to create some sort of "subfolders" inside a package in Eclipse just to visually divide files in groups?
Try to use working sets. This won't organize your classes, but help you to display just you need at a moment.
I have some documents and an ontology for some concepts. Are there any frameworks that automatically extracts those concepts from the given documents and creates triples? The ontology must contain special properties?
I found UIMA, but as far as I understood with UIMA I can do only something like this:
create some dictionaries which keep associations with the ontology
use this dictionary with ConceptMapper
write a CAS consumer that creates the triples and persists them -
I don't like this approach because I have to keep in sync the concepts from the ontology and the dictionary.
Can be UIMA used differently, or are there any advanced frameworks that can use directly my ontology with lets say some custom properties as input and based on it annotate the documents?
I want to use ontologies as domain model because I want to create further a knowledge base and ontologies seem more flexible than for example relational model.
Thanks.
After spending more time searching on Google I found GATE and more specifically OntoRoot Gazetter and Large KB Gazetteer.
OntoRoot Gazetteer is a type of a dynamically created gazetteer that is, in combination with few other generic GATE resources, capable of producing ontology-based annotations over the given content with regards to the given ontology. This gazetteer is a part of ‘Gazetteer_Ontology_Based’ plugin that has been developed as a part of the TAO project.
I didn't test them but these ones seem good solution candidates for my problem.
What are (If there are) the differences between a Simulink library and a model reference. There's advantadges in using either of them in different situations?
The main purpose of libraries and model reference are the same: facilitate the reuse of simulink models. When you work with libraries, simulink "imports" the content of the referenced models in to the main model. Sometimes, this leads to the developer dealing with gigantic models (more than 50k blocks), which can be time consuming. When you are designing a library, the lib file cannot be run. You have to "instantiate" it in the main model. On the other side, model reference deals with separated models. They are put together when you press the simulate button, but during the design time, you deal with completely separated models. With model reference, you can also select acceleration methods (it basically compiles the model) and this can't be done with libraries.
Adding some more to danielmsd's answer:
Configuration Management: Model references can be put easily into
version control and developers can work independently from each other. A library is one file, so the blocks
cannot be versioned individually and developers cannot work in parallel.
You can protect model references.
Code Generation: Incremental build is only possible with model referencing.
BUT:
Model referencing has quite a few limitations, so check them out carefully before picking this option. See Model Referencing Limitations.
From a system design perspective model references should be used for components of your system. That is the different parts your system is made from. Libraries should be used as utilities. That is reuable blocks that are used through out your design.
For example a robot control system includes components: navigation, control, path_plannen etc. These are components and should be implemented with model references. In that case they are developed as independent models and can be tested independently.
Inside the components you could need utility blocks such as low_pass_fileter, error_state_handler and check_input_range, they are libraries.
Advantages of mdl ref:
- Code generation: Model references allow partial builds when using the coder product. Assuming you have a really large model with 100k blocks and it takes 20 minutes to build, splitting it up in model references will reduce the build time since only the changed model will need to rebuild.
Model update: only changed model references are updated "CTRL+D" therefore this helps when having really large models.
Simulation: In simulations mdl refs are generated as dlls which makes your simulations much faster (the effect is much bigger than the difference between normal and accellerator mode)
Disadvantages pains:
- In general Mdl referencing is somehow a pain to use due to limitations
There is no possibility to pass a Simulink.parameter.object which has a tree structure. (When using type:BusObject only the value property has a structure, the other properties don't)
When a subsystem has a bus signal as input, a mdl ref needs a bus object to specify the input interface, and the library block doesen't. (Even if its quite ugly to use unspecified bus inputs in a lib block). (Note that busobject are always global in the base workspace... risk of naming collisions)
I'm new to the Entity model thing and i'm looking for an advise how to organize my Entity model.
should i create one entity model file (.edmx) which will contain all the tables in my database or should i break it logical files for user, orders, products, etc.
Please let me know which one is better and what the pros/cons (if any) of each alternative.
Thanks.
I'm going to go against the grain here. I've built 2 large applications with EF now, one with a single edmx and one with several. There are pros and cons but generally I found life to be much easier with one edmx. The reason is that there is almost never a real separation of domains within an app, even if there appears to be from the start. New requirements pop up asking you to relate entities in different edmx's then you have to refactor and continually move things around.
All arguments for dividing will soon be obsolete when EF 5 introduces Multiple Diagrams, which is the only real benefit for dividing edmx files in the first place. You don't want to have to see everything you're not working on and you don't want a performance impact.
In my app with the divided edmx's we now have some duplicate entities to get the benefit of navigation properties. Maybe your app has a true separation of domains, but usually everything connects to the user. I'm considering merging two of the now but it will be a lot of work. So I would say keep them together until it becomes a problem.
Having one big EDM containing all the entities generally is NOT a good practice and is not recommended. You should come up with different sets of domain models each containing related objects while each set is unrelated and disconnected from the other one.
Take a look at this post where I explained this matter in detail:
Does it make sense to create a single diagram for all entities?
i think we should keep multiple edmx files in our project. it's like 1-edmx file -- one aggregate (collection of related objects). as per ddd (domain drive design) we can have more than one aggregates in our model. we can keep one edmx file for each aggregate