I'm working on a DSL in Microsoft's new M Grammar, and it needs to allow decimal values. I've defined decimal as
token digits = "0".."9";
token spot = ".";
token decimal = digits+ | digits+ spot digits+ | spot digits+;
That seems to work, but is there a better way? It just feels like I'm missing something.
After much digging I found that you can use the build in Language.Grammar.Decimal. As in
syntax Cost = Language.Grammar.Decimal
The Language.Base "namespace" also has some useful bits. Both Language.Base and Language.Grammar are built in to intellipad.
Related
(It's been a while since I've been here.)
I've been using the first version of PHRets v1 for years, and understood it well enough to get by, but now I'm trying to understand the advantages of v2.6.2. I've got it all installed and the basics are working fine. My issues are pretty much with comprehending fine points of query syntax that goes into the rets=>Search() statement. (I'm much more familiar with SQL statements). Specifically, I'd like to have a query return a list of properties, EXCLUDING those which already have the status of "Sold".
Here's where I am stuck: If I start with this
`$results = $rets->Search('Property', 'A','*',['Select' => 'LIST_8,LIST_105,LIST_15,LIST_19,listing_office_shortid']);`
That works well enough. BUT I'd like to fit in a filter like:
"LIST_15 != Sold", or "NOT LIST_15=Sold"...something like that. I don't get how to fit/type that into a PHRets Search().
I like PHRets but it is so hard to find well-organized/complete documentation about specific things like this. Thanks in advance.
As in my comment above I've figured out that the filter goes in the third argument position ('*', as in the original question). The tricky thing was having to find a specific "sold" code for each class of properties and placing it in that position like so: '(LIST_15=~B4ZIT1Y75TZ)', (notice the =~ combination of characters that means "does not equal" in this context). I've found the code strings for each of the property types (not clear WHY they would need to be unique for each type of property: "Sold" is Sold for any type, after all) but the correct code for a single-family residential property (type 'A' ...at least for the MLS in which I have to search is:
$results = $rets->Search('Property', 'A','(LIST_15=~B4ZIT1Y75TZ)',['Select' => 'LIST_8,LIST_105,LIST_15,LIST_19,listing_office_shortid']);
(again, the code to go with LIST_15 will be different for the different types of properties.) I think there is a better answer that involves more naturalistic language, but this works and I guess I will have to be satisfied with it for now. I hope this is of some use to anyone else struggling with this stuff.
I have a piece of code in which I call a function with argument of a string value. The string value is taken from a string array using the index.
if (validateRejectionCategory(rejectionData[0])) {
......
}
In this case is 0 still considered a magic number? Should I abstract 0 to a variable like REJECTION_CATEOGRY_POSITION? Does the function name not make it clear enough that the value would be a rejectionCategory?
Let me know your thoughts please.
In general extracting every numerical value to a constant is a bad habit. You have to maintain balance as with all things in life. Here it's clear that you want to validate the first element of rejectionData. Most uses of 0, 1, 2 are not magic, but are used in an algorithm.
You usually want to extract numeric values that aren't easily explainable in the context of code.
E.g. if your code looks like this in some main-like file:
app.modalTimeooutSeconds = 3.0
it's not really more readable to rewrite it as
let timeoutSeconds = 3.0
app.modalTimeoutSeconds = timeoutSeconds
unless you want to have a config file that are constants are stored, but you may not have enough constants to support having such a file.
Everything is context dependent and there are no good answers.
Is there any neat method to convert "1,112" to integer 1112, instead of 1?
I've got one, but not neat:
"1,112".split(',').join.to_i #=> 1112
How about this?
"1,112".delete(',').to_i
You may also want to make sure that your code localizes correctly, or make sure the users are used to the "international" notation. For example, "1,112" actually means different numbers across different countries. In Germany it means the number a little over one, instead of one thousand and something.
Corresponding Wikipedia article is at http://en.wikipedia.org/wiki/Decimal_mark. It seems to be poorly written at this time though. For example as a Chinese I'm not sure where does these description about thousand separator in China come from.
Some more convenient
"1,1200.00".gsub(/[^0-9]/,'')
it makes "1 200 200" work properly aswell
The following is another method that will work, although as with some of the other methods it will strip decimal places.
a = 1,112
b = a.scan(/\d+/).join().to_i => 1112
I would do using String#tr :
"1,112".tr(',','').to_i # => 1112
If someone is looking to sub out more than a comma I'm a fan of:
"1,200".chars.grep(/\d/).join.to_i
dunno about performance but, it is more flexible than a gsub, ie:
"1-200".chars.grep(/\d/).join.to_i
String count = count.replace(",", "");
As part of a chat app I'm writing, I need to use regular expressions to match asterisks and underscores in chat messages and turn them into <strong> and <em> tags. Since I'm terrible with regex, I'm really stuck here. Ideally, we would have it set up such that:
One to three words, but not more, can be marked for strong/em.
Patterns such as "un*believ*able" would be matched.
Only one or the other (strong OR em) work within one line.
The above parameters are in order of importance, with only #1 being utterly necessary - the others are just prettiness. The closest I came to anything that worked was:
text = text.sub(/\*([(0-9a-zA-Z).*])\*/,'<b>\1<\/b>')
text = text.sub(/_([(0-9a-zA-Z).*])_/,'<i>\1<\/i>')
But it obviously doesn't work with any of our params.
It's odd that there's not an example of something similar already out there, given the popularity of using asterisks for bold and whatnot. If there is, I couldn't find it outside of plugins/gems (which won't work for this instance, as I really only need it in in one place in my model). Any help would be appreciated.
This should help you finish what you are doing:
sub(/\*(.*)\*/,'<b>\1</b>')
sub(/_(.*)_/,'<i>\1</i>')
Firstly, your criteria are a little strange, but, okay...
It seems that a possible algorithm for this would be to find the number of matches in a message, count them to see if there are less than 4, and then try to perform one set of substitutions.
strong_regexp = /\*([^\*]*)\*/
em_regexp = /_([^_]*)_/
def process(input)
if input ~= strong_regexp && input.match(strong_regexp).size < 4
input.sub strong_regexp, "<b>\1<\b>"
elsif input ~= em_regexp && intput.match(em_regexp).size < 4
input.sub em_regexp, "<i>\1<\i>"
end
end
Your specifications aren't entirely clear, but if you understand this, you can tweak it yourself.
I'm trying to generate UUIDs with the same style as bit.ly urls like:
http://bit [dot] ly/aUekJP
or cloudapp ones:
http://cl [dot] ly/1hVU
which are even smaller
how can I do it?
I'm now using UUID gem for ruby but I'm not sure if it's possible to limitate the length and get something like this.
I am currently using this:
UUID.generate.split("-")[0] => b9386070
But I would like to have even smaller and knowing that it will be unique.
Any help would be pretty much appreciated :)
edit note: replaced dot letters with [dot] for workaround of banned short link
You are confusing two different things here. A UUID is a universally unique identifier. It has a very high probability of being unique even if millions of them were being created all over the world at the same time. It is generally displayed as a 36 digit string. You can not chop off the first 8 characters and expect it to be unique.
Bitly, tinyurl et-al store links and generate a short code to represent that link. They do not reconstruct the URL from the code they look it up in a data-store and return the corresponding URL. These are not UUIDS.
Without knowing your application it is hard to advise on what method you should use, however you could store whatever you are pointing at in a data-store with a numeric key and then rebase the key to base32 using the 10 digits and 22 lowercase letters, perhaps avoiding the obvious typo problems like 'o' 'i' 'l' etc
EDIT
On further investigation there is a Ruby base32 gem available that implements Douglas Crockford's Base 32 implementation
A 5 character Base32 string can represent over 33 million integers and a 6 digit string over a billion.
If you are working with numbers, you can use the built in ruby methods
6175601989.to_s(30)
=> "8e45ttj"
to go back
"8e45ttj".to_i(30)
=>6175601989
So you don't have to store anything, you can always decode an incoming short_code.
This works ok for proof of concept, but you aren't able to avoid ambiguous characters like: 1lji0o. If you are just looking to use the code to obfuscate database record IDs, this will work fine. In general, short codes are supposed to be easy to remember and transfer from one medium to another, like reading it on someone's presentation slide, or hearing it over the phone. If you need to avoid characters that are hard to read or hard to 'hear', you might need to switch to a process where you generate an acceptable code, and store it.
I found this to be short and reliable:
def create_uuid(prefix=nil)
time = (Time.now.to_f * 10_000_000).to_i
jitter = rand(10_000_000)
key = "#{jitter}#{time}".to_i.to_s(36)
[prefix, key].compact.join('_')
end
This spits out unique keys that look like this: '3qaishe3gpp07w2m'
Reduce the 'jitter' size to reduce the key size.
Caveat:
This is not guaranteed unique (use SecureRandom.uuid for that), but it is highly reliable:
10_000_000.times.map {create_uuid}.uniq.length == 10_000_000
The only way to guarantee uniqueness is to keep a global count and increment it for each use: 0000, 0001, etc.