symbols | 易学教程

In Common Lisp, is there a function that returns a symbol from a given string?

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问题 I want >(??? "car") CAR >((??? "car") '(1 2)) 1 I can't seem to find a function that does this. 回答1: Are you looking for this? (eval (read-from-string "(car '(1 2))")) Gives: 1 UPDATE: How about (funcall (intern "CAR") '(1 2)) ? :) 回答2: There are a few, depending on exactly what you're wanting to do. First, intern, this will return an existing symbol by that name, if it exists and will otherwise create a new one. Second, find-symbol, this will return the symbol, if it exists and nil otherwise

How to compile PHP 5.5.19 with OpenSSL 1.0.1 on OS X

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问题 I've installed OpenSSL 1.0.1j to /usr/local/ssl and now I'm trying to compile PHP 5.5.19 using this version of OpenSSL. Here is my procedure to configure... export CFLAGS="-arch x86_64" export CXXFLAGS="-arch x86_64" export LDFLAGS="-L/usr/local/ssl/lib" export CPPFLAGS="-I/usr/local/ssl/include" ./configure \ --prefix=/usr/local/php5 \ --mandir=/usr/share/man \ --infodir=/usr/share/info \ --sysconfdir=/etc \ --with-config-file-path=/etc \ --with-zlib \ --with-zlib-dir=/usr \ --with-apxs2=

Cannot download microsoft symbols when running cdb in a windows service

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问题 I have a .NET windows service that is calling cdb.exe to analyze crash dumps. I want to download the symbols from http://msdl.microsoft.com automatically when needed, using the argument: -y srv*c:\symbols*http://msdl.microsoft.com/download/symbols If I run the application as a console application, It works as expected and it downloads the needed symbols for each dump. The problem is when I start the app as a windows service, the symbols are not downloaded and, if I turn symnoisy on, at cdb's

Linker errors 2005 and 1169 (multiply defined symbols) when using CUDA device functions (should be inline by default)

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问题 This question is very much related to: A) How to separate CUDA code into multiple files B) Link error LNK2005 when trying to compile several CUDA files together Following advice from here: https://meta.stackexchange.com/questions/42343/same-question-but-not-quite and here https://meta.stackexchange.com/questions/8910/asking-a-similar-but-not-the-same-question I am asking a very similar question but I want to be absolutely clear about where is the difference between my question and the

In Rails models; for symbols get automatically converted to YAML when saving to DB. What is the correct approach?

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问题 In my model example Game, has a status column. But I usually set status by using symbols. Example self.status = :active MATCH_STATUS = { :betting_on => "Betting is on", :home_team_won => "Home team has won", :visiting_team_won => "Visiting team has one", :game_tie => "Game is tied" }.freeze def viewable_status MATCH_STATUS[self.status] end I use the above Map to switch between viewable status and viceversa. However when the data gets saved to db, ActiveRecord appends "--- " to each status. So

Ruby on Rails - Get object association values with array of symbols

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问题 For example, have the models: class Activity < ActiveRecord::Base belongs_to :event end class Event < ActiveRecord::Base has_many :activities attr_accessible :foo end I can get the activity's event foo by using activity.event.foo (simple enough). But I want to make a generic function that finds out first if an object has a belongs_to association and then get that object's foo through the belongs_to association (pretend that all objects have a foo through the belongs_to association)? So far I

Django Form values without HTML escape

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问题 I need to set the Django forms.ChoiceField to display the currency symbols. Since django forms escape all the HTML ASCII characters, I can't get the $ ( € ) or the £ ( £ ) to display the currency symbol. <select id="id_currency" name="currency"> <option value="$">$</option> <option value="£">£</option> <option value="€">€</option> </select> Could you suggest any methods to display the actual HTML Currency character at least for the value part of the option? <select name=

How do I echo ASCII art that contains special characters in a batch file?

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问题 So.. This is (to me anyway) the most important feature of this program. I need this to work. Please don't laugh.. (okay you can laugh) but when my program errors, I want it to display this: _ _,---._ ,-',' `-.___ /-;' `._ /\/ ._ _,'o \ ( /\ _,--'\,','"`. ) |\ ,'o \' //\ | \ / ,--'""`-. : \_ _/ ,-' `-._ \ `--' / ) `. \`._ ,' ________,',' .--` ,' ,--` __\___,;' \`.,-- ,' ,`_)--' /`.,' \( ; | | ) (`-/ `--'| |) |-/ | | | | | | | |,.,-. | |_ | `./ / )---` ) _| / ,', ,-' ,'|_( /-<._,' |--, | `--'--

Meaning of Symbol %>% in R [duplicate]

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问题 This question already has an answer here : What does %>% mean in R [duplicate] (1 answer) Closed 5 years ago . I am an entry level R user.May be this question sound like easy but it will be great if some one can help . what is the meaning of this symbol in R-coding ... %>% Thank you 回答1: %>% means whatever you want it to mean, in Base R anyway: > %>% Error: unexpected SPECIAL in "%>%" (which means that symbol is not defined.) Binary operators are ones that have an input from the left and from

Undefined symbols for architecture i386:问题解决

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这里优先感谢 azhou_hui ，大部分内容引用自他的博文，增加了一种错误可能，部分有增删，原文传送门 http://blog.csdn.net/azhou_hui/article/details/18312047 ***************************我是无节操的分割线**************************** 多个人共同操作同一个项目或拷贝项目时，经常会出现类似这样的问题： Undefined symbols for architecture i386: "_OBJC_CLASS_$_xx文件名", referenced from: 大概有下面4种可能，前三种网上好多人都说过了，而其中第四种情况是最近刚刚被困绕过的，如果前三种方法都使用后也不能解决，可以考虑排查一下第四种可能； 1.相关工程文件未导入你可以直接在这里＋进来，也可以在左边工程目录中把文件全部重新导人一遍(多人操作工程时，一般这种解决办法) 2. .framework文件未导入把xx文件库＋进来，本问题"_OBJC_CLASS_$_ASIdentifierManager", 就是因为 AdSupport.Framework类库未加 3.文件路径缺失检查是否某些文件路径未加入进来或者写错了 4.所提示的文件内创建了未实现的类的对象这种情况多是由于编码人员失误造成的，只在