[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Problems with Entities (was re:Embed and validation)
I'm seeing some disturbing similarities between Peter's problem and mine. It reflects a general problem that I've seen in many other languages. There seems to be two schools of thought about where declarations should go: (1) Declarations must be performed near the top of the file. (2) Declarations should be performed near where they are used. Method (1) works well for declarations that are going to be referenced many times throughout the file, and is able to accommodate the cases where a reference only occurs once. Method (2) works well for declarations that are only referenced once, but works rather poorly for ones that are referenced many times throughout the file. Which school is right? I think the trend is to allow either. Take for example C vs C++. C required you to define all your variables at the top of a function, but C++ also allows you to define them just before you use them. I don't think anyone would argue that the additional flexibility is a bad thing. Method (1) requires that the user be able to establish "order" in the file (i.e. make sure the declarations occur at the top). This greatly hinders creating files with declarations in them "on the fly". In order to know what declarations will be used, the user must perform a first pass on the data before writing it out. This is not always possible and is seldom desirable. I realise this inflexibility is something that has been inherited from SGML, but I worry that this will impede XML's adoption into the marketplace. This is the second time I've had to reject using XML's entity substitution capabilities because of the need to declare all your entities at the top of the file. I originally had wished to use the entity substitution as a text substitution, but unfortunately, my users will want to "re-define" the value of an entity several times throughout the file. This cannot be done using XML entities. The entity substitution capabilities within XML seem to get me 50% of the way to where I want to be on a couple of different issues (file inclusion and text substitution), but unfortunately, I've had to choose alternative solutions because they don't get me 100% of the way. :( Rob xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i... Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ To (un)subscribe, mailto:majordomo@i... the following message; (un)subscribe xml-dev To subscribe to the digests, mailto:majordomo@i... the following message; subscribe xml-dev-digest List coordinator, Henry Rzepa (mailto:rzepa@i...)
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