Manage static UDFs

Manage q static user-defined functions (UDFs):

deleteUDF           remove UDF from server
getUDFInfo          get UDF metadata
saveUDF             register a UDF on the server
getUDFDescription   get UDF description in reader-friendly format

You can also manage q static UDFs through the command-line interface.

saveUDF

Define a UDF on the server

saveUDF `funcName`func`description!(funcName;func;description)

Where

  • funcName is the name of a function as a symbol atom
  • func is a function or a string that parses as a function
  • description is a string describing the function

The function is checked against the restrictions below and stored on the server. Any previous function of the same name is overwritten. If the restrictions are violated, saveUDF signals an error.

Example:

name:`testGetTicks

fn:"{[dict]
    k:`symList`dataType`assetClass`startDate`endDate`startTime`endTime; 
    getTicks k!(`;`quote;`moneyMarket),dict`sD`eD`sT`eT }"

desc:"This function is a wrapper for getTicks. 
    It has 4 inputs, sD, ed, sT, eT,
    which are startDate, endDate, startTime and endTime respectively."

saveUDF `funcName`func`description!(name;fn;desc)

To protect the server from user code that could permanently harm it, saveUDF parses incoming q UDF code and checks it against the following restrictions:

  • takes a single dictionary argument
  • refers to no global variables or functions besides API functions (getStats, getTicks, etc.) and native q functions (e.g. joins), some .Q utilities, and some .z objects
  • no disk operations
  • opens no handles between processes (hopen)
  • no system calls
  • parses no strings (e.g. get"hopen 5346" will fail)
  • no exit calls

Note

Comment lines in the func argument cause an error. UDFs are parsed on loading to confirm that they are structured correctly. Keep the func argument free from comments and copy the code with comments into the description argument.

getUDFInfo

Get UDF metadata from the server

getUDFInfo enlist[`funcNames]!names

where names is a list of UDF names as a symbol vector or atom, returns a table of information about the UDFs. The null symbol ` in names selects all defined UDFs.

The result table has columns:

funcName     symbol    name of the UDF
funcExists   boolean   whether defined in the system 
funcCode     string    code for the UDF
description  string    description of the UDF

Example:

getUDFInfo enlist[`funcNames]!enlist `testGetTicks

A single-key dictionary needs the arguments of Dict enlisted.

deleteUDF

Remove UDFs from the server

deleteUDF enlist[`funcNames]!enlist names

where names is a list of UDF names as a symbol vector or atom, deletes the corresponding UDFs from the server. (The null symbol does not select all UDFs.)

Example:

deleteUDF (enlist`funcNames)!enlist `testGetTicks

getUDFDescription

Return the UDF description in a reader-friendly format

getUDFDescription enlist[`funcNames]!enlist names

where names is a list of UDF names as a symbol vector or atom, returns the corresponding UDF descriptions in a reader-friendly format. (The null symbol does not select all UDFs.)

getUDFDescription (enlist`funcNames)!enlist `testGetTicks

Executing UDFs