If this Boolean attribute is set, this option is not checkable. Often browsers grey out such control and it won't receive any browsing event, like mouse clicks or focus-related ones. If this attribute is not set, the element can still be disabled if one of its ancestors is a disabled element.
If present, this Boolean attribute indicates that the option is initially selected. If the element is the descendant of a element whose multiple attribute is not set, only one single of this element may have the selected attribute.
The content of this attribute represents the value to be submitted with the form, should this option be selected. If this attribute is omitted, the value is taken from the text content of the option element.
A somewhat common occurrence when dealing with optional valuesin combination with Result is the case where one wants to invokea fallible fallback if the option is not present. This exampleparses a command line argument (if present), or the contents of a file toan integer. However, unlike accessing the command line argument, readingthe file is fallible, so it must be wrapped with Ok.
If you disagree with a VA decision dated on or after February 19, 2019, you can choose from 3 decision review options to continue your case: a Supplemental Claim, a Higher-Level Review, or a Board Appeal. You can request only one decision review per issue at a time. Keep reading on this page to find out which option is right for you.
Note: You can request an optional, one-time, informal conference with a higher-level reviewer to identify specific errors in the case. If you request an informal conference, this may delay the review.
The value None is used when an option does not have an actual value. Otherwise, the expression Some( ... ) gives the option a value. The values Some and None are useful in pattern matching, as in the following function exists, which returns true if the option has a value and false if it does not.
In the previous code, a list is searched recursively. The function tryFindMatch takes a predicate function pred that returns a Boolean value, and a list to search. If an element that satisfies the predicate is found, the recursion ends and the function returns the value as an option in the expression Some(head). The recursion ends when the empty list is matched. At that point the value head has not been found, and None is returned.
Many F# library functions that search a collection for a value that may or may not exist return the option type. By convention, these functions begin with the try prefix, for example, Seq.tryFindIndex.
The openFile function in the previous example has type string -> File option because it returns a File object if the file opens successfully and None if an exception occurs. Depending on the situation, it may not be an appropriate design choice to catch an exception rather than allowing it to propagate.
Additionally, it is still possible to pass null or a value that is null to the Some case of an option. This is generally to be avoided, and typically is in routine F# programming, but is possible due to the nature of reference types in .NET.
There is a module, Option, that contains useful functions that perform operations on options. Some functions repeat the functionality of the properties but are useful in contexts where a function is needed. Option.isSome and Option.isNone are both module functions that test whether an option holds a value. Option.get obtains the value, if there is one. If there is no value, it throws System.ArgumentException.
The Option.bind function executes a function on the value, if there is a value. The function must take exactly one argument, and its parameter type must be the option type. The return value of the function is another option type.
The option module also includes functions that correspond to the functions that are available for lists, arrays, sequences, and other collection types. These functions include Option.map, Option.iter, Option.forall, Option.exists, Option.foldBack, Option.fold, and Option.count. These functions enable options to be used like a collection of zero or one elements. For more information and examples, see the discussion of collection functions in Lists.
Options can be converted to lists or arrays. When an option is converted into either of these data structures, the resulting data structure has zero or one element. To convert an option to an array, use Option.toArray. To convert an option to a list, use Option.toList.
Data erasure On removes files and cleans the drive. If you're planning to donate, recycle, or sell your PC, use this option. This might take an hour or two, but it makes it harder for other people to recover files you've removed.
Data erasure On removes files and cleans the drive. If you're planning to donate, recycle, or sell your PC, use this option. This might take an hour or two, but it makes it harder for other people to recover files you've removed.
Which program will be the best option for serving meals to children in your community? To help you decide, we have created a chart to show how SFSP, traditional school meals, and the Seamless Summer Option compare.
Options are a type of derivative product that allow investors to speculate on or hedge against the volatility of an underlying stock. Options are divided into call options, which allow buyers to profit if the price of the stock increases, and put options, in which the buyer profits if the price of the stock declines. Investors can also go short an option by selling them to other investors. Shorting (or selling) a call option would therefore mean profiting if the underlying stock declines while selling a put option would mean profiting if the stock increases in value.
The main disadvantage of options contracts is that they are complex and difficult to price. This is why options are considered to be a security most suitable for experienced professional investors. In recent years, they have become increasingly popular among retail investors. Because of their capacity for outsized returns or losses, investors should make sure they fully understand the potential implications before entering into any options positions. Failing to do so can lead to devastating losses.
Both options and futures are types of derivatives contracts that are based on some underlying asset or security. The main difference is that options contracts grant the right but not the obligation to buy or sell the underlying in the future. Futures contracts have this obligation.
In finance, an option is a contract which conveys to its owner, the holder, the right, but not the obligation, to buy or sell a specific quantity of an underlying asset or instrument at a specified strike price on or before a specified date, depending on the style of the option. Options are typically acquired by purchase, as a form of compensation, or as part of a complex financial transaction. Thus, they are also a form of asset and have a valuation that may depend on a complex relationship between underlying asset price, time until expiration, market volatility, the risk-free rate of interest, and the strike price of the option. Options may be traded between private parties in over-the-counter (OTC) transactions, or they may be exchange-traded in live, public markets in the form of standardized contracts.
An option is a contract that allows the holder the right to buy or sell an underlying asset or financial instrument at a specified strike price on or before a specified date, depending on the form of the option. Selling or exercising an option before expiry typically requires a buyer to pick the contract up at the agreed upon price. The strike price may be set by reference to the spot price (market price) of the underlying security or commodity on the day an option is issued, or it may be fixed at a discount or at a premium. The issuer has the corresponding obligation to fulfill the transaction (to sell or buy) if the holder "exercises" the option. An option that conveys to the holder the right to buy at a specified price is referred to as a call, while one that conveys the right to sell at a specified price is known as a put.
The issuer may grant an option to a buyer as part of another transaction (such as a share issue or as part of an employee incentive scheme), or the buyer may pay a premium to the issuer for the option. A call option would normally be exercised only when the strike price is below the market value of the underlying asset, while a put option would normally be exercised only when the strike price is above the market value. When an option is exercised, the cost to the option holder is the strike price of the asset acquired plus the premium, if any, paid to the issuer. If the option's expiration date passes without the option being exercised, the option expires, and the holder forfeits the premium paid to the issuer. In any case, the premium is income to the issuer, and normally a capital loss to the option holder.
The holder of an option may on-sell the option to a third party in a secondary market, in either an over-the-counter transaction or on an options exchange, depending on the option. The market price of an American-style option normally closely follows that of the underlying stock being the difference between the market price of the stock and the strike price of the option. The actual market price of the option may vary depending on a number of factors, such as a significant option holder needing to sell the option due to the expiration date approaching and not having the financial resources to exercise the option, or a buyer in the market trying to amass a large option holding. The ownership of an option does not generally entitle the holder to any rights associated with the underlying asset, such as voting rights or any income from the underlying asset, such as a dividend.
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